270 BOTANICAL GAZETTE [march 



by which it becomes less responsive to germinative conditions. The following 

 conditions caused the secondarily dormant seeds to germinate: removal or 

 partial removal of the testa; redrying of the soaked seeds; short exposures 

 to high or low temperatures; treatment with acids (especially no. 01 HCl and 

 propionic); treatment with high concentrations of carbon dioxide followed 

 by germination in air. High partial pressures of oxygen had no effect on the 

 germination of secondarily dormant seeds. 



The authors give the following interpretation of this work: "It wiU be 

 seen that the main interest of this communication centers around the causes 

 underlying the initiation of growth rather than in the conditions of dormancy. 

 In considering this question of growth in the case of seeds of B. alba, our experi- 

 ments show clearly that there is no question of limiting factors. We have 

 been able to trace no limiting factor responsible for the non-germination of 

 white mustard seeds showing secondary dormancy. We find ourselves rather 

 in the presence of facts which emphasize a conception of stimulus. It has been 

 seen that widely different treatments, quite unclassifiable in any feature other 

 than that they all result in injury and death, if carried too far, excite germina- 

 tion and growth of white mustard seed. It appears to us probable that some 

 return will have to be made to this conception of stimulus in plant physiology 

 generally, and that in any experimental analysis of the living plant, as a unit 

 and in relation to its life-cycle, the idea of limiting factors, which has so long 

 dominated the minds of plant physiologists, will have to be modified." — Wm. 

 Crocker. 



Chondriosomes in plants. — Investigations dealing with chondriosomes have 

 become so numerous that it seems worth while to make a brief summary of the 

 results obtained. As might be expected, a few structures of different nature 

 have been called by the same name; but a host of names have been apphed 

 to the same structure, so that we have mitochondria, chondriosomes, chon- 

 driomites, chondriokonts, chromidia, sphaeroblasts, histomeres, plasmosomes, 

 cytomicrosomes, etc. The "chondr," meaning a small grain, was chosen 

 because most of the bodies are in the form of small granules; the "mito," 

 meaning thread, is often suggestive, because the granules have a tendency to 

 become arranged in rows. The terms mitochondria and chondriosomes will 

 probably survive, and if a choice should be made between these two, it should 

 be the latter, since it is noncommittal; while the fact that the threadlike 

 arrangement is by no means imiversal is an objection to the term mitochondria. 

 The name chromidia was applied because the writer believed that the granules 

 were portions of the chromatin extruded from the nucleus. Suth granules 

 certainly occur in animals and possibly in plants, but they are not the same 

 structures as the chondriosomes. 



A historical resume of the subject, with a very complete bibliography up 

 to 1 9 14, was compiled by Cavers,'' and in an investigation upon the rela- 



4 Cavers, F., Chondriosomes (mitochondria) and their significance. New 

 Phytol. 31:170-180. 19 14. 



