60 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



The invertible sugar consists of saccharose. The limits of the amounts 

 found in the various flowers examined were, for reducing sugar, from 1.27 

 to 4.88 per cent, of the normal undried substance, and, for invertible 

 sugar, from traces to 2.12 per cent. The average of the amounts found 

 in the leaves collected at the same time as the flowers was 2.2 per cent. 

 After being cut and exposed to the air, the proportion of sugar in the 

 flowers was reduced, which, according to Boussingault, is due to oxida- 

 tion, with formation of carbonic acid. This action takes place only in 

 the green state, becomes feeble during desiccation, and is inappreciable 

 in the dried product. While for this liberation of carbonic acid or of 

 oxygen reasonable explanations may be found without great difficulty, 

 it will not be as easy to explain the liberation of hydrogen gas by vege- 

 tation, which, the observations of Pollacci seem to indicate. Thus he 

 found that Oidium Tuclceri found on grape-leaves is rapidly destroyed 

 when exposed to the action of sulphureted hydrogen, and he therefore 

 believes that the destruction of this fungus by application of sulphur is 

 due to this gas formed by the action of nascent hydrogen, probably lib- 

 erated by the leaves and fruit in the process of growth. This action la 

 indicated by the results obtained by washing the leaves which had been 

 treated with pure sulphur with distilled water and testing the washings 

 with lead acetate and silver nitrate. Similar experiments made upon 

 other plants led him to the conclusion that all plants are capable of lib- 

 erating hydrogen in a nascent condition. Missanghi, however, takes 

 issue with Pollacci in his conclusions, but appears to have misunderstood 

 them. He experimented with a view to the determination of emission 

 of hydrogen in the growth of mildew, and by subjecting the atmosphere 

 surrounding the fungus growing on bread to suitable tests, he was un- 

 able to detect the slighest trace. While these results are of value with 

 reference to mildew, they do not seem to conflict with those of Pollacci. 



But whatever may be the character and composition of the gases lib- 

 erated by plants in respiration. Ad. Mayer finds that between this latter 

 function and growth, as determined by experiments made ui)on small 

 wheat-plants under various conditions, no fixed relation exists. Growth 

 is variable, depending upon very many external conditions, while respi- 

 ration, the quantity of oxygen, and the character of the plants being 

 similar, is remarkably constant. 



From the con sideration of these questions we nowpass to those of a more 

 technical character, among the most important of which are the conclu- 

 sions of Soxhlet and Tisserand with reference to manufacture of butter. 

 The former, in a discussion upon the condition of fat in milk, opposes 

 the generally-accepted theory that it exists in globules surrounded by a 

 membrane which it is necessary to break uf) in the process of churning, 

 or by chemical means, lor the production of butter, and believes that 

 it exists in much the same condition as oil in an emulsion with albumin, 

 citing authorities in support of his belief. He considers that in new 

 milk the butter is present in oily drops, as it appears under the micro- 

 scope ; but his experiments show that if the milk is frozen at a tempera- 

 ture of three or four degrees below 0° C, they become solid and remain 

 in this condition after the milk is thawed. It can then be separated by 

 churning, it is said, in two minutes, a result usually requiring eleven 

 minutes ; which is a point of great practical importance. The conclu- 

 sions of Tisserand, who has made an extended series of experiments 

 upon the influence of low temperatures, varying from 0° to 30.0^ C, upon 

 milk and the production of butter, are similar to those of Soxhlet; for he 

 finds that it renders the separation of the cream more rapid, increases 

 Its volume and the yield of butter, and improves the quality of tho 



