72 NOTES AND MEMORANDA. 



By horizontal and sagittal sections, as also by measurements of the 

 drawing and the uncut object, the results obtained may be checked. 



Though this plan may seem somewhat tedious, the author says 

 that the result rej^ays the trouble, as so plain a view of the object 

 examined could not easily be obtained in any other way.* 



Microscopy at the Paris Exhibition. — It seems to be agreed by 

 those who visited this Exhibition that there was literally nothing new or 

 calling for special remark either in Microscopes or accessories. Micro- 

 scopes were included in Class 15, " Instruments of Precision," whilst 

 Class 8, " Methods and Material of Higher Education," contained 

 most of the Microscopic preparations exhibited, some of which were 

 also included in Class 14, " Medicine, Hygiene and Public Assistance ;" 

 Class 12, "Photographic Apparatus and Photographs," contained 

 Micro-photographs. The jurors in Class 15 were Lord Lindsay (for 

 England), MM. Bardoux, Cornu and Laussedat, and Commandants 

 Mouchez and Perrier (for France) ; Dr. Fleischl (for Austria-Hun- 

 gary) ; Signor Colombo (for Italy) ; M. Broch (for Sweden and 

 Norway) ; and M. Soret (for Switzerland). 



We have endeavoured to compile a list of the gold, silver, and 

 bronze medals and honourable mentions awarded to opticians and 

 others for Microscopes, &c. ; but as these were not separately classed, 

 it is impossible to distinguish with complete accuracy the cases in 

 which the award was made for Microscopes, or for some of the other 

 instruments exhibited in conjunction with them. The difficulty would 

 obviously not be solved by taking the names of those opticians who are 

 makers of Microscopes only, and under these circumstances we must 

 leave the official list to speak for itself. 



The Generation of Gas in the Protoplasm of living Protozoa.— 



The discovery that gas is generated in the protoplasm of Arcella under 

 the influence of volition, and serving for a hydrostatic purpose,f gave 

 rise to the conjecture that other Protozoa living free in water might 

 be able to make use of this simple means of vertical motion. Professor 

 T. W. Engclmaun says J that his occasional attemj)ts to confirm this 

 supposition have led to a positive result in at least two instances. 



He found on the surface of some water which was taken from 

 a ditch richly covered with duckweed, a spherical Sphoerojplirya, 

 measuring • 08 mm. which contained a large air-bubble. The species 

 was distinguished by its size, and also by thirty to forty relatively 

 very long ('12 mm.) and thin suctorial filaments regularly spread 

 over the surface of the body ; and also by numerous small con- 

 tractile vesicles placed at some distance under the cuticle. It 

 may be called /^p7i. hydrostatica. When the animal came to be ex- 

 amined, the air-bubble occupied about the fourth part of the volume 

 of the body, it was situated immediately under the cuticle, and had in 

 a tangential direction a long oval shape. In four minutes it disap- 

 peared, decreasing very gradually, and at the same time becoming 



* ' Zoologischer Auzeiger,' vol. i. p. 369. 



t See Pfliiger's ' Archiv fiir die ges. Physiologie,' vol. ii. 



X ' Zoologischer Anzeiger,' vol. i. p. 152. 



