66 BULLETIN OF THE 
which forms the gastric coecum, grow round and envelop the brown body, 
so that the brown body passes as a whole into the alimentary tract of the 
young Flustra.” It seems to me that the burden of proof of such a 
remarkable occurrence lies with him who asserts its existence, and cer- 
tainly sufficient evidence is not presented by Haddon. 
To settle this question in my own mind, I cut a series of thin sections 
through a part of a stock of Escharella (which in budding shows a prac- 
tical identity with Flustra), in which all stages of regenerating polyp- 
ides were to be found. From complete series, at critical ages, I utterly 
failed to find any indication of the inclusion in toto of the brown mass 
by the polypide. But I found the alimentary tract of the polypides 
usually applied to the brown body (pyd. dgn.), as shown in Figure 92. 
At this stage the degenerated mass is surrounded by spindle-shaped cells, 
and just within these by a homogeneous or lamellated sheath. At later 
stages the elements of the degenerated mass were seen to be more loosely 
associated. The cells of the alimentary tract at the same time appear 
highly granular, and a granular coagulum often partly fills the alimentary 
tract. Before the new polypide is ready to expand itself, the brown body 
as such has often wholly disappeared. Just as my sections, leave no 
chance for the brown body to be included en masse by the alimentary 
tract, so too do they yield no evidence of the addition to the latter of 
new cells from this degenerate mass, as Ostroumoff, in the sentence 
quoted above, implies. 
The interesting facts of degeneration in Bryozoa deserve a more careful 
study than I have been able to give them. We are quite ignorant of the 
physiological significance of the regularly recurring degeneration and 
regeneration in certain Bryozoan colonies. Ostroumoff (786%, p. 339) has 
offered an interesting hypothesis, to the effect that the degeneration of 
the polypides, the remains of which are taken into the stomach of the 
regenerated polypide and the undigested portion of which is cast out with 
the fæces, is a method of excretion, made necessary to these animals from 
lack of urinary tubules. 
IV. Origin of the Gemmiparous Tissue in Phylactolemata. 
After having found that in Paludicella and the marine Bryozoa, as in 
Phylactolsemata, the growth of the colony takes place at the margin or 
tips, and that it is here primarily that buds originate, and after having 
thus found that throughout the group all of the organs of the polypide 
are derived from two layers, of which the inner gives rise to organs so 
