72 H. MARSHALL WARD, 



that the differences referred to are of no morphological importance 3 

 and only depend on obscure conditions which make themselves felt 

 during the development of the spores in the sporangium. 



In the case of the typical spores formed in the sporangia on the 

 submerged roots, the spherical shape is maintained until the moment 

 of germination ; but in those sporangia which ripen outside the liquid, 

 it often happens that the ripe spores present the appearance repre- 

 sented in fig. 12. This, however, is simply due to an infolding of the 

 spore membrane, consequent on the loss of water, a fact which may 

 easily be proved by partially drying any of the spores slowly and at a 

 low temperature ; or a similar result follows if the water is extracted 

 by means of alcohol or glycerine. In both cases the plump spherical 

 shape is immediately restored on the addition of water, but of course 

 the spores long treated with the reagents are killed. Spores contracted 

 in the former manner, however, germinate at once and normally 

 exactly as do those taken from the submerged sporangia : if dried very 

 thoroughly, however, it may require several days before the swollen 

 spore germinates in w T aterj and of course it is possible to carry the 

 desiccation too far unless very great care is taken. 



Germination. 



The normally ripened spore is at once capable of germination, and 

 the process is usually completed in from 12 to 24 hours, at ordinary 

 temperatures. 



The germination is easily observed as follows. A sporangium 

 ripened in or out of the water (there are no further differences to be 

 noted, and the following description applies to spores obtained from 

 both sources) is broken open by means of a sharp clean needle, and 

 the point of the instrument is then immersed in a small drop of water 

 on a perfectly clean glass slide : some of the spores attached to the 

 needle are left behind in the drop of water, and the whole is then 

 placed in a moist chamber, and kept at the ordinary temperature of 

 the laboratory. In a few hours germination commences, and the 

 escape of the contents of the spores as myxamcebse is completed in 

 from 12 — 24 hours, even when the temperature has varied between 

 20° C. and 15° C. 



In order to study the details of this process, and to cultivate the 

 myxamoebee further for even long periods (several weeks) I have 

 successfully employed a method well known in Germany but still far 



