XII. 



BEPORT ON THE MYCETOZOA OF THE SOUTH MIDLANDS 

 FOR THE YEARS 1895 TO 1898. 



By James Saundehs. 



Read at Watford, 28th March, 1899. 



How the development of the Mycetozoa is affected by varying 

 climatal conditions in successive seasons is well worthy of notice, 

 and has been aptly exempHHed in the years now under review. 



In the early part of the year 1895 occuiTcd the great frost of many 

 weeks' duration which has been recorded in our * Transactions ' by 

 Mr. Hopkinson. (See Vol. IX, pp. 89 and 228.) Just before the 

 commencement of this frost the writer observed a large mass of 

 Plasmodium of Badhamia utricularis on a decayed oak log in 

 IJirchin Grove Wood, Flamstcad, Herts. It was then streaming 

 in large veins over the sheltered side of the log, that is. the side 

 turned from the sun, being the most moist, 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 commenced 

 on a Thursday towards the end of February, and on the following 

 Sunday afternoon a visit was made to the spot to note the behaviour 

 of the Plasmodium. It was found that the whole mass had become 

 encysted when the frost commenced, forming a wax -like substance 

 known as " sclerotium." In this condition it had withstood the 

 excessive cold, and, in the three days subsequent to the commence- 

 ment of the thaw, the largest portion had reassumed its plastic 

 condition and was again streaming out in its characteristic veins 

 and fans. A small portion of the sclerotium still remained 

 unrevived, being in the highest and driest position on the log. 

 A gathering of the plasmodium was made, which after a few 

 weeks' cultivation fruited satisfactorily. 



Asa 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 Birchin Grove Wood in November, 1894, 

 and was allowed to encyst itself and then kept as sclerotium until 

 November, 1896 ; and that 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. 



The autumn of 1896 was excessively wet, the mean rainfall in 

 Hertfordshire in September being 6"51 inches, and in October 

 3 46 inches, these two months having together more than half as 

 much rain as fell in a whole year in 1887 and 1898. As a con- 

 sequence, all accumulations of refuse vegetation, such as leaf heaps 

 and straw heaps, were saturated in the autumn, and continued so, 

 at least in the lower parts of such masses, during the ensuing 



