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 during the coming winter students who have access to therm will break up with a couple of fine needles some tubes of Melicerta, they will find that a very few will contain a living female rotifer. She may have same eggs with her in the tube, hui more probably she will have none. If the tube contains no female rotifer, then it will probably, in about one out of five instances, be found to contain either eggs or developed males, or perhaps both. In the very first tube I opened the female had gone, devoured by her offspring perhaps, but there were four of these free swimming rotifers, They were very lethargic, and seemed startled by my rude intrusion. One or two of them were like eggs struggling into life. I found them in every stage short of real activity, and in one or two specimens I found them incompletely developed and associated with ordinary female eggs, a fact which showed that the developed specimens were not visitors to the tubes, but were bred and born there. The way to recognise a male egg in M. ringens is to look for the mastax. The fact that the male has a mastax leads me to think that for a time it is in a slate of growth, and that the spermatic secretions are not ripe until it has left the parent some hours, or perhaps days. It is possible that then the mastax and stomach may dwindle into insignificance, while the other organs increase in importance. The difficulty of following particular individuals will make it by no means easy to learn its whole life history, The mastax is developed very early, while the egg is in the womb of the mother. In examining some slides of dissections of the mastax of M. ringens, presented to me by the Rev. Lord Sydney Godolphin Osborne, and lately exhibited at the Royal Microscopical Society on the reading of a recent paper there, I found that on one slide there were six eggs, and that one of these exhibited a mastax in a forward state of development, and I believe it is a male egg. That the male should have a mastax at all is singular, as usually these males are mere spermatic bags, without mouth or stomach, very active and lively, but apparently requiring no food at all. But the mastax of the male Melicerta is very easily recognised; it differs from that of the female in being much more regular; it is shaped something like a W inverted; it is very busy organ, and even protrudes at times from the disc itself. The facts above stated support the view that the tube of Melicerta is not only a protection to the animal when living, but harbours the eggs when the animal dies, while they also load me to think that the time to seek the male is the end and beginning of the year.

With respect to the act of coition, that mush be no doubt usually concealed by the tube, but we recognise what a delicate sense of touch these rotifers must possess, when we reflect) that they are able to recognise the salutation of the suitable male, and that they permit it to lave access lo the tube. The remarkable disproportion, again, in the size of the male rotifers deserves attention; large male rotifers would be quite useless as they simply could not enter the tube. We see, too, that the absence of stomach and mastax in some, and the diminution of the size of these organs in others, leave room for an increased supply of the mere important secretions. What Melicerta, for instance, requires us essentials in her male is a size which shall be in inverse proportion to