THE MYCETOZOA 145 



sporangia, the element shown in Fig. 41, 2, may be the 

 converse of this : the formation of a nucleus by the confluence 

 of chromidial granules. 



In Fig. 41, 5, the formation of a capillitium tube by the 

 confluence of chromatic granules is evident. 



The details in Fig. 41 were drawn from one section 

 of a group of sporangia of Arcyria incarnata, the different 

 sporangia present being at different stages of evolution : 

 they are numbered as I think they come in order of age 

 beginning with the youngest. 



Fertilisation. In Fig. 40, E, is shown the union of two 

 amoebulae with fusion of the nuclei ; the converse of cell- 

 division. The amoebulae are gametes and the fusion of 

 the two nuclei marks the completion of fertilisation in the 

 zygote. The chromosomes in the nuclei before conjugation 

 Jahn found to number 8, and after conjugation, 16 ; the 

 number lost in the reducing divisions being restored on 

 conjugation. Nuclei with the reduced number are termed 

 haploid, in distinction from the diploid or unreduced nuclei. 



In many algae and fungi reduction takes place after 

 fertilisation. 



Chromidial elements. Anyone who may have the good 

 fortune to find Didymium difforme growing profusely from 

 year to year a few yards from his study door, and will 

 examine every phase in the living state and in sections, 

 will, I do not doubt, find the chromidial stages described in 

 Part IV. Nodules such as that shown in Fig. 36, 2, 3, 



10 



