802 PROCEEDINGS OF THE SOCIETY. 



The negatives were obtained in series representing successive planes or 

 foci of the object, and these in particular, as also those of Navkula 

 Smithii mentioned later, were exposed to direct light only ; no oblique 

 light, screens, intensification or reduction, or any mechanical process of 

 photographic manipulation whatever, being allowed to come into play to 

 produce what I thought might make a good picture : and, ' en paren- 

 these,' I may here say that the exasperating character of the illusion pro- 

 duced and the false images obtained by the use of oblique light have 

 rendered many of my negatives apparently useless, except from the stand- 

 point of seeing what an observer can do with an oblique pencil of light 

 faultily illuminating a partially opaque object with irregular surfaces". 



" Navkula Smithii has been very useful to me in my studies, and I 

 have observed it under many conditions. I have not seen it look like 

 the illustration in Dr. Spitta's book, ' Microscopy,' where, however, it 

 figures mostly as an example of the performance of a modern lens. My 

 photographs, on the other hand, revealing minute detail, are representa- 

 tions of the appearances displayed by all of the specimens in my posses- 

 sion, and though not germane to my investigation, are shown now 

 because they may be of interest to the biologist. I refer particularly to 

 the structure of the raphe, the central nodule, and the hyaline area. 

 Here also I take the opportunity of bringing forward photographs illus- 

 trative of an unnamed specimen found by Mr. Firth in some material 

 from Oamaru, which display features either new or strikingly abnormal, 

 and I append micrographs of the raphe of Pinnularia cardinalis and the 

 basal structure of Triceratiumfavus, as being good and instructive illus- 

 trations of their several characteristics. 



" Conditions. — Illuminant, electric arc : alternating current 220 

 volts ; periodicity 83, with suitable resistance and transformer ; average 

 use = 18 amperes 36 volts ; carbons cored 9 mm. ; candle power 1000 

 (estimated). Auxiliary condenser. 'Substage condenser, oil-immersion 

 N.A. 1 "40. Objective, 2 mm. apochromatic homogeneous oil-immersion 

 N.A. 1-40. Compensating ocular x 18. Tube length, 160 mm. 

 Camera length, 250 mm. Backed plate, speed 225 (H. and D.). Xo 

 screens. Direct light. Exposure, 18 seconds. Developer, metol- 

 hydrokinone." 



The President said the Society was greatly indebted to Dr. Butcher 

 for the exhibit of photomicrographs. He felt sure that Dr. Butcher, 

 who had been working away independently, iu the scanty leisure of a 

 busy practitioner's life, would welcome criticism or appreciation from 

 any one who understood microphotography and diatoms. 



Mr. A. E. Hilton said, in reference to his exhibit, the place in 

 nature of Mycetozoa, so far as it can be determined, is indicated, at the 

 present time, by a disposition to classify them along with Rhizopoda, 

 which are but one remove from Monera, the lowest forms of animal life. 

 The metamorphoses of Mycetozoa, however, mark them off as an entirely 

 distinct group. Their life-history presents three principal phases ; these, 

 in their natural order, being aquatic, amoeboid, and aerial. 



In the aquatic stage, highly microscopical and free-swimming swarm- 

 spores, each having a nucleus and flagellum, multiply by repeated 



