12 



BOTANY 



PAET I 



ill 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. Among the ^^ 



Bacteria, Avhich, as the cause of infectious diseases and 

 of decomposition, have been the object of so much recent 

 investigation, we also meet with spherical, rod-shaped, 

 filamentous, and spirally wound forms (Fig. 4). The next 

 stage in the progressive development of external form in 

 the vegetable kingdom is exhibited by such plants as 



Fio. C— Portion of Cladophora glomerata. 

 (X 48.) 



Fi(!. 5. — UIca Lftctuca, 

 young stage, show- 

 ing apex and base. 

 (X 2-20.) 



Fig. 7.—Cladostephus verticillatvs. (After 

 Prinosiieim, X 30.) 



show a DiFFEHKNTfATioN INTO APEX AND BASE. The base serves as 

 a point of attachmojit, while growth is localised at the apex. In 

 this way a growing i)oint is developed at the apex. As an example 

 of such a form, a young plant of the green Alga, Ulva Laduca (Fig. 5), 



