154 THE AMERICAN MONTHLY [Sept 



The Egg. — An egg (fig. M) is a primordial cell set 

 aside for reproduction. While developing, the nucleus 

 in the yolk separates just as in the case of the amoeba, 

 (fig. N). The two cells then form four (fig. 0) and the 

 four form eight (fig, S) and so on until the entire yolk is 

 occupied and there arise three distinct layers called 

 epiblast (fig. T, c.) hypoblast, d, and the mesoblast, e. 

 Upon these, as fundamental principles, all animal and 

 vegetable structure is built. 



Micro-Studies in Marine Zoology. 



By James Hornkli^, Jersey, Eng. 



A new series will be at once begun and considerably 

 improved. The slides will be increased in number to 20, 

 an increase of six, each of the four members of the maga- 

 zine will range from 28 to 32 pages or more. The plates 

 will number three or four in each number. A new 

 feature will be the introduction of numerous figures in 

 the text. The radical feature of improvement will be 

 however, that all the text will relate to the slides and the 

 plates. There will be no miscellaneous articles. Each 

 instalment, of slides and its corresponding number will 

 be confined to a single class or phylum as the case may 

 be, and hence the issue will be on systematic lines. 



The Third Series will treat of the Protozoa, Sponges, 

 Hydrozoa, »nd Actinozoa — one instalment to each. There 

 will be no danger of duplication of slides already in 

 Subscribers' cabinets, as the author will issue with each 

 number a list of slides proposed to be sent, together 

 with an alternative list from which substitutes may be 

 selected for such as may not be desired in the other list. 



The number to be issued first will deal with the 

 Sponges, and will comprise some unique preparations. 

 Special attention will be taken in the ringing of the 

 glides to secure permanency. 



