58 PHARMACEUTICAL BOTANY 



istics. Similarly among the bacilli characteristic forms result as single individuals 

 and others which form chains of various lengths. 



Rapidity of Growth and Multiplication. — The rapidity with which bacteria 

 grow and multiply is dependent upon species and environment. The rapidity of 

 the growth is surprising. Under favorable conditions they may elongate and divide 

 every 20 or 30 minutes. If they should continue to reproduce at this rate for twenty- 

 four hours a single individual would have 17 million descendants. If each of these 

 should continue to grow at the same rate, each would have in twenty-four hours 

 more, 17 million offspring, and then the numbers would develop beyond conception. 

 However, such multiplication is not possible under natural or even artificial condi- 

 tions, both on account of lack of nutritive material and because of the inhibition 

 of the growth of the bacteria by their own products. If they did multiply at this 

 rate in a few days there would be no room in the world but bacteria. 



Chemical Composition of Bacteria. — The quantitative chemical composition 

 of bacteria is subject to wide variations, dependent upon the nutritive materials 

 furnished them. About 80 to 85 per cent, of the bacterial body is water; proteid 

 substances constitute about 50 to 80 per cent, of the dry residue. When these are 

 extracted, there remain fats, in some cases wax, in some bacteria traces of cellulose 

 appear, and the remainder consists of i to 2 per cent. ash. 



The proteids consist partly of nucleo-proteids, globulins, and protein substances 

 differing materially from ordinary proteids. Toxic substances known as endotoxins 

 to distinguish them from bacterial poisons secreted by certain bacteria during the 

 process of growth, also occur. 



SUBDIVISION III.— ALGiE 



Low forms of thallophytes of terrestrial and aquatic distribution 

 consisting for the most part of single cells or rows of single cells 

 joined end to end to form filaments. They contain chlorophyll or some 

 other pigment, and so can use the CO2 and H2O in the same manner 

 as higher plants, e.g., in assimilating and providing for their own 

 nutrition. 



Class I. — Chlorophyce^, The Green Alg^ 



In this group the cells are observed to possess distinct nuclei and 

 bodies, whose pores contain an oil-like pigment called chlorophyll, 

 the chloroplasts. The following forms are typical : Spirogyra, Diatoms, 

 Pleurococcus, Volvo.x, Conferva, and Chara. 



Class II. — Ph^ophyce^, The Brown Alg^ 



Mostly marine forms showing great diversity in the form of their 

 vegetative bodies. Their bodies are usually fixed to some support in the 



