September i, 1923] 



NATURE 



329 



especially in England and America, we realise to our 

 dismay how much we are behind in our results, and how 

 bad are the Conditions under which we are working 

 and are likely to work for some time. We have, how- 

 ever, in accordance with our possibilities, achieved a 

 certain amount of work which, I hope, may be of 

 interest to our colleagues in physiology and physiological 

 chemistry. I can only give the main results we have 

 obtained, but it provides an insight into the trend of 

 scientific thought which has prevailed in Russia during 

 the period of isolation. 



Soon after the post-War conditions had brought 

 about a state of affairs in which it became difficult to 

 feed the population and the available food became less 

 and less, Russian scientific men were faced with the 

 task of investigating various nutrition problems. A 

 number of emergency substitutes such as bran, oil- 

 cakes, straw, etc., were suggested to the public. It 

 became necessary, therefore, to establish a standard 

 according to which the nutritive value of the different 

 substitutes could be assessed. As in Germany, it 

 became at first necessary to prepare bread with various 

 grasses and to mix large quantities of potatoes in the 

 flour. The conditions under which a bread could be 

 prepared that could be employed as a basal-food 

 product had to be worked out. It became necessary 

 to make use of the experience of other countries, 

 especially Austria. At one time the advisability of 

 feeding on whole-meal bread, as was done in Italy, was 

 considered. This, however, was found unsuitable and 

 uneconomical. Then we had to set to work in order 

 to find out how a number of natural foods such as 

 plants and roots. Lichen islandicus, Laminaria digitata, 

 could be utilised. With this purpose in view, a series of 

 metabolism experiments were carried out with bread 

 to which these substitutes were added. The most 

 successful results were obtained with Laminaria, of 

 which 70 per cent, was utilised by the system ; 25 per 

 cent, of Iceland moss and quantities up to 50 per cent, 

 of various green plants were also found to be assimilated. 

 Of course plants are not utilised well, owing to the high 

 content of cellulose, and several methods were con- 

 sidered in order to overcome this difficulty. One way 

 considered was to pulverise the cellulose and free it 

 from lignin; another, to bring the cellulose into a 

 soluble state. 



In this connexion a Swedish preparation known as 

 " Swedish flour " was of interest to us. This product 

 consists of pure cellulose and is ideal in its physical 

 consistency. It is light, porous, and does not irritate 

 the intestine in the slightest degree. Metabolism 

 experiments have, however, revealed that the output 

 was equal to the intake, and that there was no utilisa- 

 tion of the product. Occasionally the output was less 

 than the intake, and in these cases the deficit could be 

 accounted for quantitatively as methane in the expired 

 air. 



The attempt to utilise bran in its entirety was of 

 greater interest. The bran was mixed and fermented 

 with lactic organisms at 40-45° C. for 15 hours. The 

 cell-membranes were thus disorganised and the cell 

 contents were m'ade available. This can also be 

 attained by means of autolysis by increasing the 

 acidity with lactic acid to a strength of o"i-o"i5 P^^ 

 cent. When autolysis is complete, flour can be added 



NO. 2809, VOL. 112] 



. and the mixture made into dough and baked. Bread 

 prepared in this way was found to be utiHsed 5-6 per 

 cent, better than a control bread, especially as regards 

 protein. It contained a large amount of protein 

 matter and vitamins. The liquid obtained by auto- 

 lysing in acid medium or by fermentation with lactic 

 organisms can also be utilised mixed with agar and 

 gelatin as a nutrient medium for organisms. ■ 



A special commission was engaged in investigating 

 the nutritive yeasts. The physiological and medical 

 part of this investigation was worked out under my 

 own supervision. It was established that nutritive 

 yeast, beer yeast, and dried yeast form ideal foods rich 

 in protein. Up to 85-90 per cent, of the material is 

 assimilated, and palatable dishes can be prepared from 

 it. Yeast alone cannot sustain life, as it does not 

 contain fats and vitamin- A. If, however, yeast is 

 mixed with a good fat it is capable of maintaining the 

 existence of rats and mice. 



Yeast, like meat extracts, promotes the secretion 

 of the gastric and pancreatic juices, and greatly 

 stimulates the action of salivary amylase and of 

 trypsin. An adult organism can tolerate as much as 

 100 gm. of yeast without harm. Only a slight increase 

 in the output of uric acid was observed. I am not 

 going to discuss now the pharmacological side of this 

 food, but I may say here that it stimulates growth in 

 children and in animals, and that it increases the 

 formation of haemoglobin in blood in general. 



Our interest in yeasts for nutritive purposes made 

 us also investigate the part played by " mineral " 

 yeasts which the Germans cultivated on ammonium 

 sulphate and glucose. These are usually a mixture of 

 bread yeast and Mycoderma cerevisice. They were 

 found to be of Httle use for nutrition purposes. 



Much more interesting were the results we obtained 

 with the so-called " Fetthefe." The Germans wanted 

 to utilise this substance as a source of fat, but were 

 not successful. We adopted a different procedure from 

 theirs. Cultures of Endornyces vernalis under certain 

 conditions can produce as much as 18 per cent, fat 

 calculated on dry matter. The investigation of the 

 fat has shown that it mostly consists of triglycerides 

 and resembles olive oil in composition. It is ^ell 

 assimilated. To prepare the fat by cultivating the 

 organism in bottles was of course too expensive, and 

 we adopted the following method of cultivation. 

 Potatoes and other vegetables poor in fats and protein 

 were sterilised and inoculated with Endornyces vernalis. 

 After 5-6 days' growth the medium was dried. The 

 product thus obtained is rich not only in carbohydrates 

 but also in nitrogenous substance and in fat, and can, 

 like the flour, be employed as a new article of food. 

 As such it can be assimilated by human beings. Ex- 

 periments are now in progress for the purpose of 

 applying this process to animal nutrition. 



When the famine abated the dietetic investigations 

 became less urgent. Russian physicians and physio- 

 logists, however, collected interesting material con- 

 cerning starvation. It is difficult to imagine the 

 degree of starvation. The table below gives the 

 official standard ration of the population according to 

 status and age for most categories of Russian populace. 

 Human life could not continue under such conditions, 

 and the mortality was great. 



