10 Transactions of the SocAety. 



are differences in form and behaviour in different organisms, in all 

 investigations by modern methods (see the writings of Faure- 

 Fremiet, Gatenby, Hirschler, Meves, Sjovall and Weigl, etc.) it 

 has been found that they have the following characteristics in 

 common ■ — 



1. They appear to be constituted of a living protoplasmic basis, 

 impregnated with or enclosed by some kind of lipoid substance 

 which is not a true fat. The chemical composition of this- 

 substance is not the same in Golgi apparatus and mitochondria, as 

 is shown by their staining reactions. 



2. They are capable eitlier of independent movement within the 

 cell or are carried about by streaming movements of the cytoplasm ; 

 sometimes we see them dispersing from a centre, other times 

 coming together to form a compact mass of granules. 



3. They grow evidently by assimilating the necessary food 

 substances from the cytoplasm, and increase in numbers by fission : 

 sometimes multiple fission in the case of the Golgi apparatus. 



4. When cell division is about to take place, the mitochondria 

 and Golgi apparatus become spread out more or less evenly in the 

 cytoplasm, so that when division actually occurs each daughter 

 cell has approximately the same number of each category of 

 cytoplasmic inclusion. 



It will be noticed that many of the activities of the mitochon- 

 dria and Golgi apparatus are characteristic of independent living 

 organisms — a similarity which has led some writers to compare 

 them to the symbiotic algas living in some Protozoa, or to bacteria 

 living in a culture medium. 



The exact behaviour of the mitochondria and Golgi apparatus 

 during oogenesis differs in detail in most cases which have been 

 investigated. That of LimnfBa, studied by Gatenby, is one of the 

 simplest {3). In this Mollusc mitochondria appear in the oocyte 

 in the form of granules on one side of the nucleus. Thev mav 

 possibly be formed under its influence as the result of the emission 

 of some nuclear stimulus. These mitochondria spread out around 

 the nucleus and become fairly regularly distributed throughout the 

 cell. During growth some enlarge more rapidly than others, and 

 all do not attain the same size. 



The Golgi apparatus of Limnsea in the earliest stages resembles 

 that of Patella, shown in Plate I, fig. 2. The archoplasm breaks 

 up and each Golgi element as it disperses carries away with it a 

 small piece of that substance. The archoplasm only divides by 

 binary fission after it has become studded with a number of Golgi 

 elements. The yolk bodies are formed under the influence of the 

 Golgi element, as is the case in Patella. 



In Helix {2) the mitochondria also appear as a cloud of 

 granules adjoining the nucleus. During dispersal they pass tlii'ough 

 a stage when they appear as small flocculent masses, but later they 



