oJ 
(oe 
“2 
Katharine Foot and E. C. Strobell 
some. A comparison of his section (Photo. 17) with our Photos. 18 to 
24, Plate I, will show that all these eight preparations represent about 
the same stage of development. The chromosomes of his section are 
quite as well formed as those in our preparations—the only difference 
being that in his section the plasmosome still persists, whereas, in our 
preparations at this stage it has disappeared. 
We think there can be no doubt that our Photos. 18 to 24, Plate I, 
represent very nearly, if not exactly, the same stage of development as 
Wilson’s section (Photo. 17) and his sketches ¢ and d, Fig. 2, of the same 
article (05). A comparison of our preparations (Photos. 18 to 24+) with 
Wilson’s section (Photo. 17) shows beyond question that there is no 
structure in our preparations which resembles morphologically the (odd) 
heterotropic chromosome (h) of Wilson’s section. We would accentu- 
ate the fact that in our preparations all the eleven chromosomes are in 
evidence and that it is, therefore, possible to establish the identity of the 
chromosome which Wilson and Montgomery interpret as their odd 
chromosome and we are thus in a position to compare it directly with 
the same chromosome figured by Wilson. Unfortunately, Wilson has 
figured only a few.of the eleven chromosomes in each of his three 
sketches, but this need not hamper the comparison, for all of our photo- 
graphs of this stage show every chromosome, making it possible for us 
to identify the eccentric—and this identification is placed beyond ques- 
tion by the fact that the later history of this chromosome can be fol- 
lowed uninterruptedly. 
In the very early first prophases as soon as the chromosomes attain 
a definite form we find as a rule nine tetrads—the two microchromo- 
somes, (often quite far apart), and one chromosome which typically 
appears as two thin parallel rods. It is this last chromosome which we 
interpret as identical with the persisting odd spermatogonial chromosome 
of Wilson and Montgomery, basing this interpretation on its individ- 
uality of form which enables us to follow it uninterruptedly through the 
early prophase to the late prophase or metaphase, where its eccentric 
position outside the ring of chromosomes, establishes its identity with 
the odd, heterotropic chromosome—Wilson and Montgomery invariably 
figuring this same eccentric position for their odd chromosome at this 
stage.“ In Photo. 18, Plate I, this chromosome is in the lower left 
“In “ The Case of Anasa Tristis”” (Science, February, 07), Professor Wilson 
says, that he has “for sometime had reason to suspect (in case of certain 
other genera) that a stage may have been overlooked in the prophases in 
which the odd chromosome temporarily loses its compact nucleolus-like 
form.” 
