12 



IJOTAXY 



the lowest divisions of the vegetable kingdom. The single plants of 

 the Beer-yeast (Saccharomyces cererisiae) are ellipsoidal ; but, from their 

 peculiar manner of growth, by budding, they form lateral 

 outgrowths, and thus often appear constricted (Fig. 2). 

 Cylindrical and also disc -shaped forms are shown by 

 various Algae. The Diatomeae (Fig. 3), in particular, 

 exhibit a great variety of spindle, canoe, helmet, and 

 fan-like shapes ; but they may all be derived from the 

 more simple spherical, discoidal, or cylindrical forms. 



1' ".. Plea Lactuca. 



young stage, show- 

 ing apex anil base. 

 x 220.) 



Fio. 0. Portion of Cluiln/,: 

 (X 48.) 



Flu. ~. <'lail"*tiiJins ivrtii-illatn.". (After 

 TRINOSHETM, x 30.) 



Among the Bacteria, which, as the cause of infectious diseases and 

 of decomposition, have been the object of so much recent investiga- 

 tion, we also meet with spherical, rod-shaped, filamentous, and 

 spirally wound forms (Fig. 4). The next stage in the progressive 



