CHEMISTRY. 



portion of one part to 100 parts of chlorophyl 

 green. Its solutions show no fluorescence, 

 notwithstanding statements to the contrary. 

 It possesses the reactions of Krukenberg's lipo- 

 chromes, in the solid state, namely : a blue col- 

 oration with sulphuric acid, the same with ni- 

 tric acid, and a green- blue with a solution of 

 iodine in potassium iodide. It shows- three 

 bands in the blue half of the spectrum, but no 

 absorption in the red, and agrees in spectrum 

 with the yellow coloring-matter of blauched 

 leaves (etioliri). Chlorophyl green possesses 

 four bands in the red half of the spectrum, 

 agreeing with the four bands of the ordinary 

 chlorophyl solution. The quantity of chloro- 

 phyl contained in plants appears to have been 

 underestimated ; for Hansen has obtained from 

 450 grammes of dried wheat-leaves from three 

 to four grammes of solid coloring- matter. 



The existence of phenol in a free state in the 

 cones, acicular leaves, and parts of the stem of 

 the Scotch pine (Pinus sylvestris) has- been 

 shown by Dr. A. B. Griffiths. The quantity 

 in the stem varies with the age of the part; 

 the older portions yielded as much as- 0-1021 

 per cent., while the young portions gave only 

 0-0654 per cent. The leaves' yielded, accord- 

 ing to their age, 0-0936 and 0-0315 percent.; 

 and the cones gave from 0*0774 to 0-0293, 

 according to their maturity. This discovery is 

 regarded by the author as tending to show that 

 the phenol of the coal-formations is derived 

 from coniferous vegetation, and as supporting 

 from a chemical point of view the opinions of 

 geologists that the conifer existed in that age, 

 It further suggests a possible origin for petro- 

 leum. The same investigator has also found that 

 farm-yard manure is highly capable of propa- 

 gating the microscopic fungi, and that the para- 

 site of the potato-disease (Peronospora infes- 

 tans), in particular, throws out its nymphse very 

 actively in it. He suggests on the basis of this 

 observation that manure may act as a medium 

 for the development and dissemination of para- 

 sitic diseases. The bacteria which are devel- 

 oped in it are, however, completely destroyed 

 by treating the manure with solutions of fer- 

 rous sulphate, cupric sulphate, or sodium chlo- 

 ride. 



Prof. F. H. Storer has made experiments on 

 the conditions favorable to the germination of 

 the seeds of weeds. Selecting the seeds of 

 Polygonum acre (water smart-weed), Polygo- 

 num^ Persicaria (spotted knot- weed), Lappa 

 officinalis (burdock), Ambrosia artemiscpfolia 

 (rag- weed), Bidens chrysanthemoides (burdock), 

 and Setaria glauca (bottle-grass), he planted 

 them in his greenhouse, where the temperature 

 was permitted to range from 48 or 50 Fahr. 

 at night, to 68 or 70 Fahr. by day. Except 

 of the knot-weed, only a very few of the seeds 

 sprouted, while by far the larger part of them 

 mildewed and were spoiled. The experiments 

 were regarded as failures, and the lack of suc- 

 cess was attributed to the fact that the tem- 

 peratures, though favorable to agriculture, were 

 VOL. xxiv. 9 A 



too low for the germination of the seeds in 

 question. Many of our commonest weeds are 

 tropical plants; and the seeds selected for these 

 experiments, excepting those of the burdock 

 and knot- weed, came from plants that flourish 

 during the hot weather of the later summer 

 months. 



The results- of some recent investigations 

 on the formation of starch in the leaves of 

 dicotyledonous plants have recently been pub- 

 lished by Prof. Sachs. For determining the 

 presence of starch he used the iodine test 

 upon the leaf after it had been plunged in 

 boiling water and immersed in alcohol fop 

 the extraction of soluble substances and color. 

 Sachs had already shown that, if a plant was 

 placed in the dark, the starch disappeared 

 from the leaves; it was- known that, if a 

 piece of tin-foil is placed upon a leaf, the 

 covered part forms no starch,, although the 

 parts exposed to the light may be filled with 

 it; and Kraus had shown that starch can be 

 formed very rapidly in direct sunlight. Sachs's 

 later experiments demonstrate on a number of 

 plants that the starch formed on the leaves 

 during the d'ay may disappear completely 

 during the night, and that the leaves shown to 

 be full of starch in the evening may be quite 

 empty of it on the-next morning. The change 

 depends upon the temperature and health of 

 the plant, but occurs normally during the 

 summer in plants growing in the open. The 

 rapidity and completion of the process depend 

 upon- the weather. It was already known that 

 the starch disappears from the leaves in the 

 form of glucose, which travels by way of the 

 vascular bundles into the stems. The results 

 of the observations made on this point led to 

 the conclusion that the processes of metamor- 

 phosis into glucose and translocation of the 

 products of assimilation, are also going on dur- 

 ing daylight, although they are less evident 

 then, because morfc starch is being formed and 

 accumulated than is abstracted at the time. 

 The starch was shown to travel in the form 

 of glucose in all of the cases ; but it was not 

 proved whether the metamorphosis was effected 

 by forces in the chlorophyl-grains themselves, 

 or by means of diastatic ferments in the cells 

 of the leaf. Sachs also directed his attention to 

 the solution of the question of how much starch 

 is produced in a definite extent of leaf-surface 

 by assimilation during any particular period of 

 exposure to bright sunlight; the experiments 

 being made to show both the quantities of 

 starch which disappear during the night and 

 the quantities formed during the day. On the 

 whole, Sachs concluded that from twenty to 

 twenty-five grains of starch may be produced 

 per one square metre of leaf-surface per day ; 

 and some plants produced much more than 

 this. The experiments prove why plants are 

 so vigorous during warm nights following upon 

 hot, bright days ; it is because the products of 

 assimilation, formed in large quantities during 

 the day, are able to pass more readily into the 



