By Professor Lindley. 



307 



and the particles which remain are not more than a half or quarter 

 their former size. I have not, however, remarked among them any 

 appearance of dissolving ; neither have I been able to observe any 

 change in the curious double-headed bodies, in form resembling 

 dumb-bells, found in the vessels of Euphorbias, and supposed to 

 be a state of amylaceous matter, because iodine colours them violet ; 

 they appeared to me to be in precisely the same state before and 

 after the plant was frozen to death. M. Pa yen, however, denies 

 that any starch whatever is lost in frozen potatoes {Comptes rendus, 

 VI. 345) ; but as only a small part of his important treatise on 

 amylaceous matter has reached this country, I am unable to state in 

 what way he explains the action of cold upon this substance. 



Finally, it appears that frost exercises a specific action upon the 

 latex, destroying its power of motion. If, as Professor Schultz 

 supposes, this is the vital fluid of plants, such a fact would alone 

 account for the fatal effects of a low temperature. In all the cases 

 I have observed frost coagulates this fluid, collecting it into amor- 

 phous masses. In Stapelia, where the laticiferous vessels are easily 

 found, the latex itself is so transparent, that it is difficult to per- 

 ceive it in a living state, even with the best glasses ; but after freezing 

 it is distinctly visible, resembling half coagulated water. In the 

 Hibiscus above mentioned, the stem is covered with long, rigid, 

 simple hairs, filled with a plexus of capillary laticiferous vessels of 

 extreme tenuity, but in which the motion of the latex may be seen 

 beautifully with the | of an inch object glass of an achromatic mi- 

 croscope. Upon being thawed, after freezing, all this apparatus 

 is found reduced to some misshapen separate sacs of fine grumous 

 matter, in which no motion can be detected. That these vessels 

 lose their vitality after freezing may indeed be seen without the 

 aid of a microscope ; for if a stem of a Ficus elastica, or a Eu- 

 phorbia, or any such plant, which discharges an abundance of milk 

 when wounded, be first frozen, and then thawed, no milk will 

 follow the incision. 



