122 INTRODUCTION TO CYTOLOGY 



Evidence in support of this conception was contributed by Forenbaelx-r 

 (1911), Pensa (1914), Cavers (1914), and others. Guilliermond (1911- 

 1920) in particular was led by the results of his extensive researches on 

 the subject to the view that the chondriosomes, arising only from preexist- 

 ing ones by division, persist through the egg and embryonic cells 

 and later become amyloplasts, chloroplasts, and chromoplasts. In 

 this he saw strong evidence for the individuality of the plastid. In 

 1915 he advanced the opinion that in fungi the chondriosomes function 

 like the amyloplasts of higher plants, forming reserve products as the 

 latter form starch. In this development of chondriosomes into plastids 

 Guilliermond (1913-1915) and Moreau (1914) were able to show that the 

 chondriosomes produce within them certain phenolic compounds which 

 either appear at once as anthocyanin pigments, or as colorless products 

 which may acquire color later through chemical alteration (Fig. 46, J5). 



Among the most recent researches in this field are those of Mottier 

 (1916, 1918) on the cells of Zea, Pisum, Elodea, Pinus, Adiantum, Antho- 

 ceros, Pallavicinia, Marchantia, and several algae. He finds that leuco- 

 plasts and chloroplasts are derived from small rod-shaped primordia 

 (Fig. 46, C, D) which he regards as permanent cell organs of the same 

 rank as the nucleus. Both primordia and mature chloroplasts multiply 

 by fission. In the cells of Marchantia, Anthoceros, and the seed plants 

 he finds also a second series of bodies, which he calls chondriosomes: 

 these like the plastid primordia, are permanent cell organs multiplying 

 by division, but they do not become chloroplasts or leucoplasts. Further- 

 more, both chondriosomes and primordia are thought by Mottier to 

 be concerned in the transmission of certain hereditary characters. 



It is also reported by Emberger (1920a6) that in the roots and spor- 

 angia of ferns two kinds of granular elements may be recognized at all 

 times, one of them representing the initial stage of plastid development. 

 Contrary to Mottier's opinion, however, he regards both kinds as true 

 mitochondria. Guilliermond (1920) likewise distinguishes two such 

 types in Iris germanica. 



P. A. and P. Dangeard (1919, 1920), as a result of their researches 

 on the cells of barley, Selaginella, Larix, Taxus, and Ginkgo, distinguish 

 three classes of cytoplasmic structures differing in .reaction to reagents 

 and in function. In their initial stages all have the granular form. The 

 plastidomes first appear as minute "mitoplasts," which gradually enlarge 

 and develop into plastids. The spheromes are at first recognizable as 

 "microsomes," some of which may be seen to give rise to fat and oil 

 globules while others appear to undergo no change. The vacuomes 

 begin their history as "metachromes;" these elongate and form a peculiar 

 network which later develops into a system of vacuoles. Guilliermond 

 (1920) denies the metachromatic nature of this third class of bodies, and 

 holds them to be quite distinct from mitochondria. 



