VETERINARY SCIKNOK AND I'RACTICK. 4S7 



(l;iy. I'luiii lliis ]i('ri(i<l tlir <l('crcast' was gradual, up to 4li() days, wlicii mily 1,4(10 

 l)ack!ria ptT grauiwiTc I'duud. 'Plic rt'sults agree witli Kiissi-ll as to tlic cnuriiujus 

 developiiu'ut of lactic-acid bacteria, l)ul differ somewhat as to the period of increase 

 and decline. The greatest increase in acidity occurred between nulling and salting. 

 From this point until the cheese was 40 days old there was a gradual increase. The 

 pri'vailing sjjecies of lactic-acid bacteria was the Baclermin acidi lactlr!. Next in 

 numlx'rs was B. lactic <rr(>gi')i('x, or a closely allied form. When cultures of these two 

 organisms were introduced into sterilized milk a tirm curd was ])roduced, with little 

 or no gas. 



The gas-pro(hicing bacteria belonged usually to either the //. coll grouj) or the B. 

 lacticHroijenes group. In the presence of the former the cheese was sometimes 

 mottled. 



The li(]uefying ))acteria were not numerous in the Canadian cheese examined, and 

 they decreased in numbers as the cheese ripened, being seldom found after 3 weeks. 

 In one instance the presence of a large number of digesting bacteria was ass(Kriated 

 with a bad flavor in the cheese. Two or three forms closely related to i>. fulvns ■ 

 were found in young cheese. This group gave rise to bad flavor or odors in milk. 



Yeasts were quite commonly found in Canadian cheese and frequently in large 

 numbers. The experiments indicate that they are the only mitTO-organisms that 

 actually increase in cheese. While the name yeasts is applied to this class, most of 

 them were species of Torula, as they formed no spores. Some were beneficial, act- 

 ing somewhat like lactic-acid bacteria, while others were injurious, causing undesira- 

 ble fermentations. One species produced a mottled appearance in the cheese. These 

 yeasts show a remarkable tolerance to acidity, so that it is difficult tc overcome thgir 

 action by the addition of a vigorous lactic-acid starter. Some grew in peptone solu- 

 tions containing 2.25 per cent of lactic acid. 



The author discusses at some length the causes of the ripening of t-heese, as sIkjwu 

 by his own work and that of others. He gives the following as •?mi)ortant facts 

 which are well supported by the evidence of careful experiments: (1) The enormous 

 nund)er of lactic-acid bacteria in hard cheese, and the very small numbers of liquefy- 

 ing or digesting bacteria; (2) the existence of galactase, a natural enzym inherent 

 in fresh milk; and (3) the ability of rennet to cause the change of nonsoluble nitroge- 

 nous i)roducts to soluble ones." 



The author's experiments with Canadian cheese indicate that the amount of acid 

 present is sufficient to inhibit the action of galactase in cheese ri[)ening, and that 

 this enzym is therefore of little importance. On the contrary, rennet acts more 

 quickly and with greater jxiwer in acid solutions. It would therefore seem that the 

 role of the lactic-acid bacteria is to create a requisite acidity, so that the pepsin of the 

 rennet can exercise its digestive action on the cheese. 



"Summarized, the ripening of cheese may be said to be caused by the digestive 

 action of the rennet on the insoluble nitrogenous matter of the cheese, in the jires- 

 entte f)f acid formed Ijy the lactic-acid bacteria. The large amount of acidity also 

 I)revents or inhibits the growth of other (and perhaps undesiral)le) species of 

 liactrria." 



Danish trade in dairy produce in 1900 {Jour. Bil. At/r. [London^, ,s' (lUOl), 

 No. ,.\ j>j). .^.JS-J.34)- — Report to the foreign othce from the British consul at Copen- 

 hagen. 



Siberian butter trade (Jour. B<1. Aijr. [Loudon], 6' [1901), No. J, pp. iiSO-^S.i). — 

 Report of H. Cooke, commercial agent of the board in Russia. 



VETERINARY SCIENCE AND PRACTICE. 



Report of the veterinarian, W. 11. Dalkvmple ( Loiii'slaiM S(((.^. Bid. 64, 2. .s-er., 

 pp. 5fi5-GJ4,Jiil>^- J I). — The station undertook to eniiourage the importation of highbred 

 cattle from the Nortii, and for tliis imrpose volunteered to imnnmi/'.e sucii cattle 



