16 EXPERIMENT STATION RECORD. 



claims tliat the power to assimilate free nitrogen is an almost universal 

 one, being possessed by many orders of plants besides tlie Leguminosw. 

 He summarizes his own results as follows: 



(1) Legumes assimilate free nitrogen even when not in symbiotic 

 relation with the tubercle fungus. 



(2) The symbiotic fungus when cultivated apart from the host plant 

 develops vigorously when it is supplied with organic combined nitro- 

 gen, but only feebly in free nitrogen. 



(3) The amount of nitrogen which accumulates in the root tubercles 

 is not sufficient to supply the amount which mature legumes, even 

 when grown in soil free from nitrogen, possess in their seeds and other 

 organs. The tubercles can not hold all the assimilated nitrogen, but 

 must give it up to the platit; of this and the way it is effected there is 

 as yet no evidence. 



(4) Kon-leguminous plants assimilate free nitrogen as follows: 

 Fungi, algic, mosses, OscUlaria, Wostoc^ Ulothrix, and flowering plants 

 as oats, buckwheat, spurry, Brass ica napus, white mustard, potato, and 

 Acer platanoides. 



(5) The value of nitrates applied to the soil is best shown when the 

 l^lants are small and the power of assimilation still weak. 



The author claims that the ability to assimilate free nitrogen is 

 more widely spread in the plant world than that of carbonic acid 

 assimilation, but that it varies in degree according to the kind of 

 plant. That it is assimilated as well by the alga as the fungus, and 

 that assimilation of free nitrogen is a function pertaining to active 

 protoplasm and the place of assimilation is in no particular plant 

 orgiin, but in all the cells under certain conditions. 



The influence of city fog on cultivated plants, F. W. Oliver 

 {Abs. in Forsch. Geb. agr. Phys., 16 {1893), No. 5, pp. 496, 497).— The 

 author found by his investigations that city fog has a twofold influence 

 on plants. The first is that it causes the light to be so greatly diffused 

 that the chlorophyll activity is interfered with and starch production 

 is greatly reduced; and the second is the direct injury done to plants 

 by sulphurous acid, hydrocarbons, and other poisonous substances 

 held in the fog. If a sound plant be brought into an atmosphere 

 charged with sulphurous acid, as in the case of thick fog, it will quickly 

 die without dropping its leaves. In dilute sulphurous acid the green 

 of the leaves gradually disappears until the plant resembles one grown 

 in the dark or in a greatly diffused light. Through the darkness due 

 to the fog the protoplasm becomes less efficient against injurious influ- 

 ences and the death of the leaves is hastened. Ferns and other shade- 

 loving plants are less influenced by city fog than plants requiring sun- 

 shine, and monocotyledonous plants less than dicotyls. 



The principal eftect sulphurous acid exerts upon plants is that it 

 causes a shrinking of the protoplasm of the cells, gaining access to 



