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 116 of the "immediate agent derived from the male organ, or the manner of its application to the ovulum in the production of that series of changes constituting fecundation." But he puts forward the opinion that a more attentive examination of the process in Orchids and Asclepiads is more likely to be fruitful of results than most other families.

He returns again to this matter of fecundation in the following year, studying several orchids, but especially Bonatea, for the purpose. He is somewhat shaken as to the validity of his former inferences, and concludes that the "mucous cords" (i.e. strings of pollen tubes) are perhaps derived from pollen "not, however, by mere elongation of the original pollen tubes, but by an increase in their number, in a manner which I do not attempt to explain." In this later paper he also hazards the suggestion that in Ophrys, as impregnation is frequently accomplished without the aid of insects, "...it may be conjectured that the remarkable forms of the flowers in this genus are intended to deter, not to attract, insects." Also he suggests that the insect forms in orchidaceous flowers resemble those of the insects belonging to the native country of the plants. This is a clear foreshadowing of what is now called protective mimicry—and the former suggestion is not at any rate wholly without modern supporters, though Brown's share in its origin seems not to be generally recognised.

The keen desire to get to the bottom of a problem, which was so outstanding a feature of Brown's whole mental attitude, unquestionably explains why he was led to make so many important discoveries in such widely different directions. His first hand knowledge of the structure of a vast number of plants gave a soundness and depth to his morphological investigations that must arouse the admiration of everyone who is acquainted with them. He was never satisfied with perfunctory attempts to solve a problem, but, as we have already seen, in the example of his studies on Asclepiads and Orchids, he would return again and again to the matter till he had satisfied himself of the accuracy of his work. It is a pity that all of the present day botanists do not follow more closely in his steps in this respect. Publication of a paper seems to some to be a matter of greater