ZOOLOGY AND BOTANY^ MICROSCOPY, ETC. 115 



Both before and during the period of ripe fruits, several species of 

 Saccharomyces are found, both in flowers (chiefly in the nectaries) and 

 on the bodies of insects ; the former being derived no doubt from in- 

 sects, who have obtained them either from other flowers, from decaying 

 fruits or other substances, or from the soil, which has been proved by 

 Hansen to be an inexhaustible storehouse of these organisms. A 

 comparatively small number are, however, at any time to be found 

 floating in the air. When the fruits are being first formed the flowers 

 have withered and dried up; if these persist round the fruit, the 

 ferments may reach the latter directly; but these organisms are 

 comparatively rare on unripe and uninjured fruits. As soon as the 

 fruit is ripe, it is attacked by various insects which puncture the skin, 

 and thus convey to the cellular tissue of the leaf the ferments of 

 which they are the carriers ; the species thus found being chiefly 

 S. apiculatus and Wurtzii. But, although this explanation suffices 

 for most fruits, it fails in tbe case of the grape, the ferments of which 

 are almost exclusively -S^. ellipsoideus and S. conglomeratus, species not 

 found on insects or flowers. Of this difficulty the author is not able 

 to offer any satisfactory explanation. With regard to fruits in 

 general, it may be stated that in the autumn the ferment is present 

 everywhere on ripe fruits that have been in any way injured ; after 

 they have fallen, the organisms are preserved partly on the debris 

 of the fruits, partly in the soil, where they hibernate. From the 

 commencement of spring they are carried by insects to flowers, and 

 finally from them to the ripe fruits. 



MICROSCOPY. 

 a. Instruments, Accessories, ^c. 



Beck's Portable National Microscope. — The object of Messrs 

 Beck in designing this instrument (fig. 1) has been to produce a Micro- 

 scopewhich should retain the rigid Jackson-Lister limb, and combine 

 with it great portability. This object has been effected by making the 

 feet of the stand to fold up and the stage to swing on a strong joint, 

 thus enabling the instrument with apparatus to be packed in a case 

 measuring lOi in. x 7^ in. x 3^ in. A large amount of useful 

 apparatus can be added without increasing the size of the case. The 

 legs, which fold up in the smallest compass, are very firm when spread 

 out. The substage has rack-and-pinion movement, and the stage, 

 which rotates concentrically, can be replaced by one with mechanical 

 movements by rack and pinion if so desired. None of the strength 

 or stability of the instrument is sacrificed for its principal feature of 

 portability. ^ 



Beck's Combined Substage Apparatus.— Whilst applicable to other 

 torms of instruments, the combined substage apparatus (fig. 2) has 

 been specially designed by Messrs. Beck for their portable " National " 



I 2 



