Further studies on the Gametogenesis of Pandarus sinuatus, Say. 233 
rounded by a cloud of chromatin graniües, in the centre of a yolkfree area, 
fig. 19. The cliromosomes have akeady begim to shorten. The plasmo- 
some disappears, and the chromosomes continue to shorten until their 
breadth equals their length, when a second, though only partial, divi- 
sion transforms them into tetrads. The first division can be distinguished 
as it is the most complete, and the tetrads become arranged on the first 
maturation spindle so that the resulting mitosis separates whole chromo- 
somes, and thus pre-reduction takes place, fig. 20. This reduction din- 
sion is easily followed in the related species, Orthagoriscicola muricata, 
fig. 22. The second maturation mitosis is equational and separates the 
halves of the resulting diads, fig. 21. A diagram of the synapsis and re- 
duction is shown in the accompanying text figure, and illustrates in ge- 
neral both spermatogenesis and oogenesis. The plasmosome and growth 
of the nucleus in the oogenesis are not represented. 
Vs. the Critique of Hagedoorn. 
Studies relating to the individuality of the chromosomes have been 
brought into special prominence owing to the debated question of the 
relation of the visible parts of the gerni cells to the factors discovered by 
analyzing breeding experiments. I will make no attempt at a general 
consideration of this subject, but wish to call attention to an argument 
brought forward in a recent paper on animal breeding. Hagedoorn i) 
says: „I do not see why we should attach any more value to the inheri- 
tance of a chromosome than to that of any other organ or character.“ 
I should like to emphasize the fact that the chromosomes and the other 
parts of the mitotic figiire are the only „organs“, to use Hagedoorn’s 
term, that are seen to be transmitted bodily to the daughter cells in cell 
division. 
In Order to depreciate the significance of the chromosomes in here- 
dity, Hagedoorn States further that „Godlewski — succeeded in ferti- 
lizing enucleated eggs of the sea-mchin with sperm of a crinoid, with the 
result that the ensuing larva — developed into a normal sea-urchin ga- 
strida“. Aow compare this with his further Statements that „AU inheri- 
tance is Mendelian inheritance“ and „It is impossible for a character to 
be in a recessive condition“ (p. 33). How can we harmonize these State- 
ments? If all inheritance is Mendelian and characters of immatm’e 
stages are on a joar with adult characters, how does he account for the 
1) Arch. f. Enhdcklungsmech., 1909, XXVIII, S. 28. 
