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 A HISTORY OF HERTFORDSHIRE pact masses, which may be separate sporangia, or the whole protoplasmic contents may coalesce and form an xthalium. But whether the fruiting- stage consists of sporangia or aethalia, these contain an immense number of spores which are eventually distributed by the wind, and when they are borne to favourable situations their life-cycle recommences. When in the motile stages, whether as amoeboid cells or as plas- modia, should the climatal conditions become unfavourable, they have the power of encysting themselves and existing apparently in a state of suspended animation. When their environment is again favourable they resume their plastic state and motile condition. In illustration of the advantage to the organism of this singular power the following facts are presented. In the early part of the year 1895 occurred a severe frost of many weeks' duration. Just prior to its commencement the writer observed a large mass of plasmodium of Badhamia utricularis on a decayed log in Birchin Grove Wood, Herts. It was then streaming in large veins, and was evidently in full vigour. Two or three days after this the frost set in, and no observations were made until its cessation. The thaw com- menced on a Thursday towards the end of February, and on the following Sunday a visit was made to the spot to note the behaviour of the plas- modium. It was found that the whole mass had become encysted when the frost commenced, forming a wax-like substance, the sclerotium. In this condition it had withstood the excessive cold, and in the three days subsequent to the commencement of the thaw, the greater proportion had resumed its plastic condition, and was again streaming in its characteristic veins and fans. A small portion of the sclerotium still remained unrevived, being in the highest and driest portion of the log. A gathering of the plasmodium was made, which after a few weeks' cultivation fruited satisfactorily. As a further illustration of the tenacity of life of the sclerotium- stage of Badhamia utricularis, the writer may mention that he has a lantern-slide of this species which was gathered in the plasmodium condition in a wood in Herts in November, 1894, and was allowed to encyst itself and then kept as sclerotium till November, 1896. After these two years of suspended animation it was easily revived by moisture and moderate warmth, when it spread itself out into its characteristic forms in search of food. It was then rapidly dried by artificial heat, so that its usual appearance in the creeping-stage should be rendered permanent. Some plasmodium of Badhamia nitens was collected in a wood in Cad- dington, Herts, at Christmas, 1892. It was attached to a fungus (Irpex) which was growing on a decayed branch of oak. The whole gathering wood, fungus, mycetozoon was frozen hard when obtained. It rapidly thawed within doors and exhibited movements for several days. A short time afterwards it was allowed to dry up, when it assumed the sclerotium condition. In this state it existed, looking like a piece of sealing-wax, until the spring of 1894. It was then placed in tepid water, and during 78