54 LECTURES ON BIOLOGY 



of the testicles of this animal, under the microscope, magnified 

 about 2,000 times, we can distinguish numerous heterogeneous 

 cell-elements, which represent different stages of development 

 from the so-called spermatoblast to the fully developed sper- 

 matozoon which is furnished with a thin caudal filament. 

 The spermatoblasts develop by direct metamorphosis from the 

 so-called protoblastic cells, i.e., the cells which evolve from the 

 epithelial covering of the vesicles. , Each of these spermato- 

 blasts splits up into two cells of equal value, called sperma- 

 tocytes of the first degree, which in their turn split up each 

 into two cells, called spermatocytes of the second degree, 

 or spermatides. These, again, change by a highly complex 

 metamorphosis into the complete spermatozoa. From each 

 spermatoblast originate, therefore, normally four complete sper- 

 matozoa supposing that the cells are favoured by luck, for many 

 cells perish at an early stage. How are we to explain this 

 remarkable phenomenon ? When I observed this development 

 for the first time in Rossia macrosoma I felt greatly puzzled, 

 but accurate comparisons with the conditions obtaining in other 

 species of cuttle-fishes and many tedious researches solved the 

 mystery. 



It is known that in the generative glands of most animals, 

 in a most highly developed form in insects, crustaceans, &c. 

 there is found, in addition to the sex-cells proper, a large 

 number of accessory cells whose task it is to supply the growing 

 spermatozoa and ova abundantly with food. Of the numerous 

 methods by which these cells fulfil their task I will mention only 

 the two most important. They either take nutriment from the 

 surrounding body-cells of the organism and transmit it to the 

 sex-cells, thus playing the part of a middleman, or they them- 

 selves serve as food and are gradually devoured by the sperma- 

 tozoa and ova. 



No such special feeding apparatus has been evolved in the 

 cuttle-fish, but Nature knows how to help herself without it. 

 At certain times there are formed in the seminal tubules of the 

 testicles of Eossia enormous numbers of germ-cells. As these 

 cells are themselves only sparsely furnished with food, the store 

 being insufficient for the growth and metamorphosis .of the com- 

 plete spermatozoa, there takes place in consequence among this 



