192 DESCRIPTION OF {Polygastrica. 



has seen glandular bodies which periodically increase in 

 size, and are analogous to the seminal glands of other 

 Infusoria. The dispersion of the ova has been seen by 

 Turpin and Meyen, though it was regarded by them as 

 that of the fecundating matter of plants. Dr. E. appends 

 the following observations to the genus : — 



*' 1. The relations of number observed in Micrasterias 

 appear to form a firm character of the species (as in 

 Gonium pectorale). 



" 2. The relations of size are not always in a ratio with 

 those of number ; for we find small size with a large 

 number, and great size with a small number of parts. 



"3. Forms exhibiting equal relations of number to size 

 otherwise distinguish themselves in secondary and less 

 important points, as in a slender or thicker form of cell, 

 long or short horns, &c. &c. ; conditions varying in almost 

 every individual. 



"4. Of the numerous forms seen by me, all were 

 two-pointed, none had one-pointed bodies. (No Pedias- 

 trum simplex). 



"5. Regularity of form is the character of integrity 

 from irregularity ; no distinct species can be formed." 



(a). Bodies ray -like, in a circle, without a central cell. 



190. Micrasterias tetras. The four-rayed Micras- 

 terias is a star-like cluster, composed of four creatures 

 connected together. (The margin is slightly emarginate.) 

 Diameter of clusters 1-1 150th to l-2300th. Size of single 

 body 1 -2300th to 1 -4600th. 



