AS RESERVE-MATERIAL IN PLANTS. 



25 



Still more striking is the effect of the vapors of ether. If 

 spirogyra-threads containing freshly produced droplets arc ex- 

 posed in a flask at ordinary temperature to the vapors of ether, 

 the cells are found killed in a few seconds, and about 20 minutes 

 afterwards all the globules change their aspect, losing their 

 brightness and their solubility ! 



The coagulation by heat is easily observed if the objects are 

 dipped in boiling water containing 5 per cent of chloride of 

 sodium, all droplets exhibiting then a turbid appearance ; neither 

 boiling water nor absolute alcohol will change them any fur- 

 ther. It is well known, that the presence of salts facilitates the 

 coagulation of albuminous matters. 



The substance in question is also changed quickly in the 

 dissolved state, with the death of the cells ; in dead cells coffei'n 

 never produces any globules. If for instance we treat Spirogyra 

 Weberi for one minute with a very dilute aqueous solution of 

 iodine, the globules may be still produced by coffei'n immediately 

 afterwards, but after 10 minutes action of the iodine, no more. 

 That our substance had not left the dead cell by osmosis can 

 be easily shown, if we add to the small quantity of the iodine- 

 solution, in which we left a larger quantity of the algae to die, 

 coffei'n in a sufficient quantity : no trace of the above described 

 phenomenon is observed. The same experiment may be made 

 with cells killed in any other way. 



All these facts demonstrate beyond a doubt, that we have a 

 peculiar protein-substance before us, distinguished from the or- 

 dinary soluble proteids not only by its being separable from the 

 dissolved state in globules by coffein or antipyrin, but also by a 

 very great lability, as these globules become coagulated by 

 influences, which do not at all change the ordinary soluble pro. 

 teids, as alcohol of 20 per cent or vapors of ether. We called 

 these globules protcosomes, thus reminding us on the one hand 

 of the proteids, on the other of the " microsomes." In the 

 coagulated state they exhibit all the properties of ordinary co- 

 agulated proteids. Treated with phosphortungstic acid (10 per- 

 cent) they remain insoluble even after weeks, while hydrochloric 

 acid of 10 per cent changes them gradually and dissolves them 

 after a series of days at ordinary temperature. — A solution of 

 •caustic soda or potash of moderate strength soon dissolves the 



