DEVELOPMENT OF SPERMATOBIUM. 13; 



roblasts and shuttle spore. In every such instance I 

 found the arrested or undeveloped sporogonium deficient 

 in or entirely without nucleus, only possessing cytospheres. 

 I believe that it is want of sufficient nuclear matter which 

 has caused the development of sporoblasts to cease. In 

 fig. 45 I have figured such a Spermatobium in which a 

 part has been arrested in its development while the other 

 has already produced spores. How this deficiency in 

 caryoplasm originated in this instance I cannot say, but 

 it may depend on two distinct causes : either the cary- 

 oplasm moved the larger part of its bulk to the part which 

 later on developed, this as I believe causing a division of 

 the original sporogonium into two smaller sporoblast, or 

 the caryoplasm may from some cause or other have been 

 destroyed in one sporoblast while not in the other. That 

 the two sporoblasts originally belonged to a single pans- 

 poroblast I judge from the remains of the original cyto- 

 theca, which is yet seen surrounding the two sporoblasts. 



NUCLEOLUS. 



But before I describe this diffusion and subdivision of 

 the nucleus proper, it will be in order to consider the 

 form, structure and nature of the nucleolus. I believe it 

 safe to say that the nucleolus is always present, even if 

 not always under the same form and of the same size. I 

 have never seen a single fully developed Spermatobium 

 which did not possess a nucleolus of some size, small or 

 large, and when the caryoplasm diffuses the nucleolus 

 remains, though sometimes in greatly diminished form, 

 until the very last, when its final division or disintegra- 

 tion takes place ; it apparently does not move with the 

 caryoplasm. 



In its perfect form, even in the intracellular stage of 

 the Spermatobium, the nucleolus consists of one single, 

 globular body, varying in size from one -third to three- 



