1900J MICROSCOPICAL JOURNAL 49 



18 to be found attached to rotten wood or on the g-rouad 

 beneath old 'logs. To prepare these, Mr. M. Barber, of 

 Kansas University, suggests that pieces of the material 

 should be placed in a warm moist place. After a few 

 hours the plasmodia will develop, and they may then be 

 fed with rotten wood or fleshy fungi. Small plasmodia, 

 for the demonstration of protoplasmic currents, may be 

 obtained by putting pieces of sclerotia in a hanging drop 

 of water, or by placing in a large cover-glass on a Plas- 

 modium and transferring it to a moist cell after the plag- 

 mOdium has run over it. 



Fixing Tentacles. — Klienberg's picro-sulphuric acid 

 is recommended for fixing zoophytes and polyioa with 

 their tentacles extended. The specimens should be placed 

 in water, and as soon as they extend themselves they 

 should ()uickly be covered with the solution. Fixation 

 follows rapidly, when, after immersion in the usual grades 

 of alcohol, they may be stained with any ordinary stain. 

 Picro-carmine gives the most satisfactory results. 



Preservatives. — Formalin is now largely used in most 

 laboratories as a preservative and fixative re-agent. It 

 does not interfere with processes of staining to any ap- 

 preciable extent, nor does it cause much shrinkage of the 

 structures operated on. Both as regards ease of manip- 

 ulation and expense, it is decide! y superior to osmic acid. 



Illuminatio::^. — A novel method of illumination, for 

 the investigation of the structure of diatoms, is suggest- 

 ed by Mr. Allan Dick in his "Notes on the Polarizing Mi- 

 croscope." A thin platinum wire is twisted into a loop 

 of just siitHcient size to allow of the passage of a darn- 

 ing needle. This wire is rendered incandescent by asi)irit 

 lamp or a Bunsen burner, and it is plac-il at a distance of 

 eight inches f .om a condenser in sucli a manner that the 

 loop may be at right angles to the axis of the microscope 

 tube. The most favorable condition for using this source 

 of illumiuatiou is when the image of the loop may be 



