128 THE MICROSCOPIST. 



CHAPTER X. 



THE MICROSCOPE IN VEGETABLE HISTOLOGY AND BOTANY. 



HISTOLOGY (from fa?, a tissue) treats of formed mate- 

 rial, or the microscopic structure resulting from the trans- 

 formation of germinal or living matter. The nature of 

 this transformation is partly physical and partly vital, 

 and, as already stated, is often so complex as to baffle all 

 chemical analysis. Some light, however, has been thrown 

 on this subject by the modification of ordinary crystalline 

 forms when inorganic particles aggregate in the presence 

 of certain kinds of organic matter. To this mode of form- 

 ation the name of molecular coalescence has been given. 

 Mr. Rainey and Professor Harting contemporaneously 

 experimented with solutions of organic colloids, and found 

 that the crystallization of certain lime salts, as the car- 

 bonate, "was so modified by such solutions as to resemble 

 many of the calcareous deposits found in nature. These 

 researches leave little doubt but that a majority of calca- 

 reous and silicious organic forms may be thus accounted 

 for. Such changes are rather physical than vital. 



Cell-substance in Vegetables. The protoplasm or bio- 

 plasm in vegetable-cells cannot be distinguished from ani- 

 mal u sarcode" or protoplasm except by the nature of the 

 pabulum or aliment necessary to its nutrition. The vege- 

 table, under the stimulus of light, decomposes carbonic 

 acid, and acquires a red or green color from the compounds 

 which it forms, while the animal requires nutriment from 

 pre-existing organisms. Yet this definition fails to apply 

 to fungi, which resemble primitive animals even in this 

 respect. So difficult is it to discriminate that the simpler 

 forms of vegetables have often been classed by naturalists 

 among animals, and vice versa. Amoeboid movements 

 have been observed in the bioplasm of vegetable-cells, 



