230 PROGRESS OF MICROSCOPICAL SCIENCE. 



vessels. Passing to the Mammalia (gays the ' Lancet,' from which wo 

 quote), he points out that the first formation of fat in the embryo 

 occurs round the kidneys, and thence gradually extends into the con- 

 nective tissue of the mesentery after birth. He considers a strong 

 argmnent in favour of the independency of the adipose tissue to be the 

 fact that it always has, down to its smallest lobules, its own proper 

 and closed system of blood-vessels, which, it is curious to observe, 

 very closely resembles that of the acinous glands. These researches 

 of Toldt" enable us to explain the absence of fat in regions where 

 everything appears to favour its formation, as in the sub-muscular con- 

 nective tissue of the intestinal canal. It explains also the persistence 

 of the tissue, with its characteristic features, even when all the oily 

 matter has been removed by absorption. Whilst fully concurring in 

 the general statement that fat-cells possess in mature adipose tissue a 

 distinct membrane, he differs from Czajewicz in maintaining that 

 when first formed they are destitute of a membrane, this only becom- 

 ing visible in the later embryonal periods. The minute masses of 

 protoplasm they contain, however, remain throughout life. He makes 

 an interesting observation to the effect that spring frogs that have 

 fasted through the winter, and are excessively lean, present fat drops 

 in which no membrane is distinguishable, but which, reduced to their 

 protoplasmic primary mass, possess the power of amceboid movements. 

 From the consideration of these facts, M. Toldt has arrived at the 

 conclusion that the protoplasm of the fat-cells, when supplied with 

 sufficient nutriment, is capable, like a gland-cell, of forming fat as a 

 kind of secretion ; and, inversely, when the consumption of oxidizable 

 material exceeds the supply, it possesses the power of using up the 

 stored-up fat and discharging it into the blood. The mode in which 

 fat is laid up has also been investigated by Fleischer, with a view of 

 determining whether, in accordance with Liebig's idea, the amylaceous 

 compounds ingested are converted into fat directly ; or whether, as 

 Voit thinks, the fat consumed in the economy is derived from the fat 

 of the food, and that the amylaceous compounds are only serviceable 

 as readily combustible compounds, by means of which the fat de- 

 veloped from albuminous compounds, and already present in the 

 body, are preserved. The results of his investigations on cows, which 

 were both numerous and extended over a long period of time, were on 

 the whole unfavourable to Voit's views. 



Presence of Fungi in the Ear. — Dr. Karsten has a paper on this sub- 

 ject, accompanied by numerous illustrations, in the ' Bulletin de la 

 Societe Imperiale ' of Moscow (No. I., 1870). The author confirms 

 the statements of Hallier and other previous observers, that when the 

 spores of these parasitic fungi arc sown elsewhere, the plants which 

 result from them assume very different forms, according as the sub- 

 stance on which they are sown is rich or poor in material for nutri- 

 tion ; and that fungi described as distinct species, or even as belong- 

 ing to different genera, are merely different genetic forms of the same 

 plant. 



Tlie Ovipositor in Bristle-tails and Spring-tails. — The last number 

 of the ' American Naturalist ' contains an extremely able though 



