98 BULLETIN OF THE 



region, the stolon, gives rise to eggs. The same condition seems to exist 

 in other Tuuicates. 



III. On some Characteristics of Gemmiparous Tissue. 



In the prgceding part of this paper the words "embryonic tissue," 

 " undifferentiated tissue," have often recurred, and they are terms in 

 wide usage in modern zoology. I do not know of any attempt to define 

 further the real character of this tissue, nor to give its more detailed 

 characteristics, other than that usually employed in the term plasma- 

 reich, or "rich in plasma." The persistence of yolk granules is, as 

 Nussbaum ('80, pp. 2-14) and Goette ('75, pp. 31, 32, 831) have shown 

 in the case of amphibian embryos, indicative of the embryonic condition 

 of cells, when these have been derived from an egg filled with yolk. 



It is very far from ray purpose to go into a detailed discussion of the 

 siguificauce of embryonic tissue, for which I am not yet fitted ; neverthe- 

 less, I wish to call attention to the minuter characters of gemmiparous 

 tissue as I have found it in Phylactoltemata and Paludicella, I have 

 described it in some detail in preceding pages. 



First, then, gemmiparous tissue seems to stain more deeply than non- 

 gemmiparous tissue in the same section. This character has been re- 

 peatedly observed before by others, and Braem calls attention to it 

 several times. I have already described how I found, by the use of 

 high powers, that much of this depth of stain was due to the unusually 

 large number of deeply staining granules scattered through the cell, but 

 chiefly gathered about the nucleus (Figs. 6, 17, 18, etc.). So marked 

 is the greater depth of the stain around the nuclei, that, with a power so 

 low that the nuclei are hardly distinguishable, their position is indicated 

 by a deeply staining band. 



Secondly, gemmiparous tissue, as I have found it in the cases referred 

 to, is distinguished by the possession of large cells, nuclei, and nucleoli. 

 I had already noticed this fact in my studies on budding in Cristatella, 

 and I find that Braem has figured the nuclei in the budding region as 

 larger than the average (cf. Braem, '90, Taf. YII. Figs. 86, 88-90). 

 My own figures show this repeatedly (Plate I. Figs. 3, 4, 5, G, Plate II. 

 Figs. 15, 17, Plate XL Fig. 99, etc.). I have also noticed this to a 

 certain extent in the marine Bryozoa, but, since the cells of the latter 

 are smaller, and as I did not succeed in obtaining from them sections so 

 satisfixctorily stained, the results are not so reliable. In attempting to 

 obtain an explanation of this phenomenon one involuntarily recalls to 



