22O W. M. SMALLWOOD. 



in the laid eggs as segmentation begins and continues, it appears 

 torn so that some of the eggs will be only partly surrounded by it. 

 Some time during the progress of cleavage this membrane disap- 

 pears entirely. It is well known that the newly deposited eggs of 

 Pennaria are inclined to stick to bits of grass, a glass dish, etc., 

 which is due to the adhesive property of the . false membrane. 

 The term false membrane is applied to this structure because it is 

 not permanent ; and the term membrane is used because it seems 

 to serve the purpose and do the work of a real membrane. No 

 differential lamellae were visible in this false membrane either be- 

 fore or after deposition. Numerous sperm heads are frequently 

 to be distinguished within its substance. The inequalities in 

 thickness of the false membrane suggest that this substance is of 

 a fluid nature in the living egg and transparent. If this interpre- 

 tation prevails, then one can no longer speak of the eggs in Pen- 

 naria as being naked. 



Second or True Membrane. After fertilization and with the 

 beginning of cleavage a second membrane begins to form (cf. 

 Hargitt) which lies in close contact with the granules of the cyto- 

 plasm and completely surrounds each cell as it is produced in 

 cleavage. This structure compares favorably in appearance, 

 staining reaction, etc., with the regularly described egg mem- 

 branes of animal eggs and so is designated as the true membrane. 



MATURATION OF THE EGG IN Pennaria. 



From the early development of the egg up to the beginning of 

 maturation I cannot add any new data, but do confirm Hargitt's 

 ('04, p. 456) observations. The extensive observations of Hargitt 

 as well as my present independent studies indicate that it is very 

 rare to find a polar body attached to the egg after deposition, 

 not one in one hundred will show a polar body at this time. It 

 is also very rare to find a deposited egg that still retains the egg 

 nucleus with a nucleolus. In fact this latter structure, the nu- 

 cleolus, has been taken as an indication of whether maturation 

 has taken place or not. Where it is lacking I have designated 

 the nucleus as the female pro-nucleus. The egg nucleus in Pen- 

 naria does not show any such great size as is found in Hydractinia 

 and varies but slightly from the female pro-nucleus which is 



