370 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
differentiated beyond the condition of a procambial string, differing in 
this respect from Rhinanthus major. When the seeds germinate without 
access to the host-plant immediately after germination, they never attain 
any considerable size or vigour. The haustoria of Euphrasia are 
exceedingly minute, and are best detected by the method of paraffin 
imbedding recommended by the author.* The initial-cells of the parasite 
which attack the host-plant commonly penetrate between the cells of the 
epiderm ; the resulting tissue advancing towards and into the vascular 
bundle of the root. The result of the attack of the parasite is distinctly 
injurious to the host-plant ; and, during the latter portion of its exist- 
ence, the mode of life of Euphrasia is to a large extent saprophytic on 
the products of the decay of the tissue of the host-plant caused by its 
attacks. Euphrasia officinalis is very seldom parasitic on any plant not 
belonging to the Gramineas. 
Formation and Transport of Carbohydrates, f — Herr W. Saposch- 
nikoff has studied these phenomena, especially in the cases of 
Helianthus annuus and Cucurhita Pepo. He finds the decrease of their 
amount when leaves are deprived of light to be only one-fifth in cut leaves 
compared to what it is in leaves still attached to the plant. The energy 
of this process shows a daily periodicity which reaches its maximum 
between 7.30 and 9.30 p.m., and its minimum between 12 and 5.30 p.m. ; 
the maximum being at an earlier period of the day than the maximum 
of growth. The presence of glucose in the cells hinders the action of 
the ferment in the further conversion of sugar into glucose. The author 
found the energy of the formation of carbohydrates in the leaves to be 
greatly influenced by the weather, being very much greater with a clear 
sky and a large amount of light. With the increase of the amount of 
carbohydrates in the leaves, the energy of assimilation proportionately 
decreases. It is obvious, from quantitative experiments, that the whole 
of the carbon of the decomposed carbon dioxide is not used up in the 
formation of carbohydrates ; there must be a second primary or secondary 
product of assimilation, which is probably an albuminoid. 
Assimilation of Nitrogen by Plants. :f — From experiments, chiefly 
on leguminous plants, Herren B. Frank and B. Otto have determined 
that green leaves contain more nitrogen in the evening than the following 
morning, and this appears to depend on the quantity of asparagin being 
larger. Asparagin and sugar are the best nutrients for the symbiosis- 
fungus ( Rhizobium ) of the Leguminosse. The larger proportion of 
nitrogen present in the evening was most striking in Trifolium pratense , 
Medicago sativa, and Lathyrus sylvestris , but was observable also, though 
to a smaller degree, in plants belonging to other natural orders. 
Effect of Transpiration on Etiolated Plants. §— Prof. W. Palladin 
explains the effect of light in retarding the growth of plants (i. e. in 
shortening the internodes) by the fact that it greatly increases transpira- 
tion. From observations made on the dried weight, as compared with 
the fresh weight, of the leaves of various plants, he concludes that 
etiolated leaves may be divided into two groups, — when sessile they 
* Cf. this Journal, 1890, p. 674. 
t Ber. Deutscli. Bot. Gesell., viii. (1890) pp. 238-42. 
X T. c., pp. 331-42. § T. c., pp. 364-71. 
