The Journal of experimental zoology . //-/ In Fig. I OF, also 17 days after fertilization, we find a stage con-siderably more advanced in which each of the middle branchiae hasalready sent out three branches, which may / be labeled accordingto age, II—I, II—2and II—3. Of these itwill be seen that II—ivery early takes onthe character of oneof the main branchialtrunks, so that we thusget a stage with fourpairs of —2 and II—3 retainthe characters of pin-nules of the Branchia II. Neither I nor IIIhas any branches atthis stage. Fig. iiA shows alater stage taken fromthe same dish at thes
The Journal of experimental zoology . //-/ In Fig. I OF, also 17 days after fertilization, we find a stage con-siderably more advanced in which each of the middle branchiae hasalready sent out three branches, which may / be labeled accordingto age, II—I, II—2and II—3. Of these itwill be seen that II—ivery early takes onthe character of oneof the main branchialtrunks, so that we thusget a stage with fourpairs of —2 and II—3 retainthe characters of pin-nules of the Branchia II. Neither I nor IIIhas any branches atthis stage. Fig. iiA shows alater stage taken fromthe same dish at thesame time (17 days).Here we still haveno branches of I and III. Branchia II hasfive branches and thefirst branch of L-II(L-II—i) a branchletof itsown (L-II—I—i)just appearing as avery small knob. Itis very evident thatBranchia II is rapidlyoutgrowing I and IIIin strength. Fig. I IB (19 days old) gives a still older stage.^Branchia I oneach side has not increased much in size and is hardly larger than. Fig. dianthus. Dorsal views. A—Age, 17 days (X47).—Age, 19 days ( X 62). 44 Charles Zeleny. the older branches of II. L-II—-i has two branchlets ( =. pin-nules) and R-II—I has one branchlet. Branchia II on each sidenow shows the beginning of the sixth branchlet or III also has not increased much in size. In Fig. 12 (23 days old) Branch II—i with its six pinnules hasvery evidently taken its place as a prominent part of the branchial
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Keywords: ., bookauthorwi, bookcentury1900, bookdecade1900, booksubjectzoology
