ZOOLOGY AND BOTANY, MICKOSOOPY, ETC. 749 



The author then describes his method for transferring the objects 

 from alcohol to paraffin. For this purpose he uses gelatin capsules 

 (20 mm. long and 7 mm. in diameter). As these 

 capsules are impenetrable to alcohol, this latter 

 must be replaced by benzol or chloroform. The 

 gelatin capsule is easily removed by immersing 

 it in water. As the resulting block is cylindrical, it 

 is made rectangular by immersion in paraffin. For 

 this purpose the brass mould is used. 



Pietsch Microtome.*— E. P. Dolby describes ^•«<<'''»'»''''«'«'' ' ^'<'<^^^^^^^^^^ 

 this instrument, whicli is a modification of the y\9. 129. 



Minot microtome, and claims that it has been 

 simplified and modified. The knife-holder is so constructed that it 

 serves both for paraffin and celloidin sections, and enables the operator 

 to note the angles of inclination most suitable for the work in hand. 

 The active part of the knife may be restricted in order to obtain the 

 greatest rigidity and to use the entire length of the edge before re- 

 sharpening. It is clamped against a three-point plane. 



The object-carrier is clamped by only one screw instead of two or 

 three, and also allows a horizontal adjustment of the preparation in 

 order to bring it close to one of the knife clamps. 



The coarse-adjustment has been greatly improved and all tlie gearings 

 reduced, both as to size and number. 



The automatic feed is entirely new. It is provided with a worm, 

 and is an inclined plane gliding on another inclined plane, the worm- 

 gear, friction and wear being thereby reduced to a minimum. This feed 

 is the only one which advances when the object is clear of the knife. 



Examining the Structure of the House-fly, Musca domestica.t — 

 0. Gr. Hewitt studied the anatomy by means of dissections of fresh and 

 preserved material under a binocular Microscope, with magnifications 

 varying from 25-65 diameters. Serial sections were made to confirm 

 the dissections and to study the histological details. Perfect series of 

 sections of the whole fly were hard to obtain, on account of the brittle 

 nature of the internal chitinous structures. Colloidin sections were but 

 little superior to paraffin sections. The best results were obtained by 

 fixing the flies for 24 hours in Henning's solution, which is nitric acid 

 16 parts, chromic acid (0'5 p.c.) 16 parts, corrosive sublimate saturated 

 in 60 p.c. alcohol 24 parts, picric acid saturated in water 12 parts, and 

 absolute alcohol 42 parts, washing out with iodine-alcohol. This fixes 

 and somewhat softens the chitin. The imbedding should not be too 

 protracted, as the chitin becomes brittle again. Serial sections of 

 recently emerged imagines made before the chitin has hardened give 

 good results. Other fixatives used were Perenyi, Rabl's chromoformic, 

 Boum's picroformol, glacial acetic acid, and absolute alcohol. The most 

 satisfactory stains were Heidenhain's iron-hffimatoxylin, Brazilin, and 

 Delafield's htematoxylin. By overstaining with the last and differen- 

 tiating with acid-alcohol perfect results were obtained. The structure 



* Trans. Amer. ]\Iicr. Soc, xxvii. (I'JOT) pp. 152-3. 

 t Quart. Journ. Micr. Sci., li. (1907) pp. 399-iOO. 



