154 BOTANICAL GAZETTE [vcusr 
tamination is unfounded. Respiration increases gradually after injury, and it 
is only after several days that the maximum activity is reached. From tha 
time the process goes on more slowly and finally returns to the normal. By 
grinding the onions with sand and expressing the juice with a Buchner press, 
he obtains solutions which liberate carbon dioxide, apparently through the 
agency of an enzyme. After injury this respiratory enzyme shows an increase 
in its activity, an increase which reaches a maximum somewhat later than the 
maximum respiration of the tissues from which the extracts are obtained. Onions 
whose cells are killed by freezing yield more active enzyme solutions than those 
not previously frozen. These expressed juices give the oxidase reaction with 
guaiacum, the juices from injured tissues moré vigorously than those from 
uninjured ones.—ARTHUR L. DEAN. 
Vines" has given the results of a number of experiments carried out for the 
purpose of throwing light on the nature of the tryptic enzymes of plants. He 
assumes that if the powers of a plant extract to convert native proteid into pro- 
teases and peptones on the one hand, and to reduce protones to the final cleavage 
products on the other, do not vary concomitantly under the influence of outside 
influences, then the two processes are carried out by separate enzymes. Exper- 
ments were conducted with the enzymes of Carica Papaya, Ananas sativus, 
Saccharomyces Cerevisiae, Agaricus campestris, Hordeum sativum, Hyacinthus 
orientalis, and Nepenthes. The proteids used were blood fibrin as 4 native 
proteid, and Witte peptone as a proteose and peptone mixture. The factors 
used to produce variation in proteolytic activity were changes in reaction. In 
every case it was found that solution of fibrin and cleavage of Witte peptone 
were affected differently by changes in reaction. Wines concludes that the 
two processes are carried out by different enzymes; the first stage by sass 
of the pepsin type; the second by those of the erepsin group. He is of the 
opinion, therefore, that pepsin-like enzymes do occur in plants and that the 
tryptic action is due to the combined action of such enzymes and those of th : 
erepsin group.—ArTHUR L. DEAN. Te 
MAssart’s?? interesting experiments with geophilous plants should have 
been noted long since. In the case of the subterranean stock he sees @ ©" 
between the depth of its burial and the development of aerial shoots. In each 
Plant, therefore, there is a most favorable depth of the subterranean stock which 
Is secured and maintained. Experiments were performed involving were 
hundred species of plants, well distributed throughout monocotyledons de 
‘dicotyledons. Each species was treated in three lots: one lot very neat as 
‘surface; another 1o°™ deep; the third 20 to 30 deep. ‘The results are Ou a 
very briefly under two heads: methods of ascending when planted eae | 
normal depth; and methods of descending when above the normal depth. ; 
71 VINES, S. H., The proteases of plants. III. Ann. Botany 19: 171-188: = ve 
*2 Massart, JEAN, Comment les plantes vivaces maintiennent leur niveau Soule 
rain. Bull. Soc. Roy. Bot. Belgique 417:67-79. figs. 12. 1903- 
