1886.] 



MICROSCOPICAL JOURNAL 



239 



laurel trees in the Experimental Gardens 

 at the State University. At first sight they 

 appeared to belong to the Aphidce, but a 

 closer inspection showed them to be 

 neuropterous insects of the genus Psocus, 

 which embraces some sixty species. They 

 are very active in the larval and pupal 

 stages, as well as in the perfect forrri. 

 They live in groups, usually on the under 

 side of the leaves. A microscopical ex- 

 amination shows them to have free mouth 

 parts. The compound eyes are exquis- 

 itely beautiful, and many other points in 

 their anatomy are of great interest. From 

 the fact that the laurel leaves upon which 

 these little creatures have made their 

 appearance in such numbers are very 

 badly infested with scale, Mr. Wickson 

 thinks it quite possible that this species of 

 Psoctis may be a natural enemy of the 

 scale insect, finding its food in the eggs or 

 young of the latter. Experiments are 

 now being carried on with a view to test- 

 ing the correctness of this conjecture. 

 A. H. Breckenfeld, Rec. Seer. 



Washington Microscopical Society. 



At the 50th regular meeting the paper 

 of the evening was by Prof. E. S. Burgess, 

 and was entitled Notes on the Larger 

 Fresh-Water Algse of the District of 

 Columbia. 



Prof. Burgess said :■ — The object of this 

 paper is to give a few hints upon collecting 

 and preserving algae and on their distri- 

 bution, in the hope that some of the 

 members may be induced to enter upon 

 this branch of microscopical study. 



1. On CoUectbig. — The time for collect- 

 ing our larger fresh-water algae, using that 

 term for those which possess visible fronds, 

 or individuals, is, according to my expe- 

 rience, in March, April, and early May. 

 Microscopic algae, it is usual and true to 

 say, are to be collected at any time of 

 year, whether winter or summer. But the 

 larger algae are not so prodigal of their 

 presence. My outfit for collecting is varied 

 at different times, according to object and 

 to the number and size of specimens 

 1 am desirous to obtain and weight I am 

 willing to carry. My favorite outfit is a 

 five-quart tin pail with cover, in which I 

 put eight wide-mouthed quarter-pint bot- 

 tles with corks. These reach just to the 

 top of the pail and nearly fill it. Between 

 the interstices they leave I place little 

 round wide-mouthed vials, such as are 

 used for homoeopathic pills, and of which 

 a gross is to be constantly kept on hand. 



A fourth requisite in this outfit is a small 

 supply of white paper cut into little oblong 



labels, an inch or two long, to be used 

 with every bottle when filled, recording the 

 place, and to be inserted into it and held 

 fast by the cork. A fifth requisite is a 

 pair of pinchers, and a sixth is a dip- 

 ping tube with a rubber bulb, to ' be 

 used in isolating small objects out of the 

 water. 



II. On Preserving. — Specimens for sub- 

 sequent microscopic examination I have 

 found best preserved by mounting in 

 King's Fresh-Water Algae Fluid, in ce- 

 ment cells, and in this it has been my 

 practice to put up one to four specimens 

 of every form collected for permanent 

 preservation and for examination of their 

 structure. This fluid may be obtained 

 from the Educational Supply Co., of Bos- 

 ton, Mass., or from Rev. J. D. King, 

 Cottage City, Mass. I have used glycerin 

 and also glycerin jelly. Glycerin con- 

 tracts the endochrome of most species by 

 absorbing Vater and is therefore undesir- 

 able. Glycerin jelly with the firmer 

 species sometimes yields good results, but 

 King's fluid does so regularly, except with 

 the Oscillarias, for which I do not yet 

 know a satisfactory medium. 



But while specimens for the study of 

 structure are best preserved in King's 

 fluid, the small size of the pai^t so preserved 

 can give, in case of the larger species, but 

 a poor idea of the external appearance 

 of the plants ; and, to supply the lack of 

 this, I formed the plan of applying to our 

 larger fresh-water algae the same method 

 as is so common with the marine forms, 

 that is, mounting specim.ens upon sheets 

 of paper or cards, so displayed as to ex- 

 hibit the branching so far as possible. To 

 these I add other specimens of the same, 

 with their branches not displayed nor 

 drawn out, but left in the position natur- 

 ally taken, to show the plant in the mass, 

 and as it is most likely to strike the eye 

 of the beginner. These card specimens 

 are prepared by floating the plant in 

 water, inserting the card under it, and 

 lifting the specimen out with such care as 

 to drain off all the water and yet leave 

 the specimen centrally placed and with 

 the disposition of its parts desired. This 

 is a much easier task with most marine 

 algse than with the soft and gelatinous 

 substance of the algae from fresh-water 

 lakes and streams, and the height of diffi- 

 culty is reached in such a plant as Tetra- 

 spora, which may float on the water in a 

 gently undulating mantle of green, thin 

 and beautiful as a lady's veil, and swaying 

 out for six or eight inches in a slow cur- 

 rent, but collapsing into hopelessly un- 



