NATURAL SCIENCES OF PHILADELPHIA. 



11 



Euglena viridis, he had observed it in great profusion on Friday last in a ditch 

 skirting the Delaware road below the coal oil depot, south of the built portion 

 of the city. The water looked in the spot as if Schweinfurt green had been 

 strewed on the surface. He also exhibited drawings of a species which 

 appeared to be an undescribed one, and which he had several times noticed 

 late in the spring and early summer some years ago. The drawings were 

 made from specimens obtained in a pond near Gloucester, N J., in May, 1858. 

 The water of the pond was thickly coated with a ferruginous red color due to 

 the Euglena. The infusorium is not of a blood-red hue, as is stated to be the 

 case in Euglena sanguinea, but is of a uniform ferruginous red. Upon keeping 

 the animalcule a few days in a glass vessel exposed to the northern light, the 

 exterior of the contents assumed a bright green hue, and the red eye point, 

 previously invisible, came into view, while the central mass of contents re- 

 mained of the original color. The animalcules remained in this condition 

 subseciuently until they died. In motion the animalcule assumed the various 

 forms observed in E. viridis and other species. It would elongate to about 

 1-I5th of a line by the l-75th of a line wide. In the resting condition assuming 

 a globular form, it measured l-37th of a line in diameter. 



The head is obtuse ; the mouth oblique ; the tail acute, and the flagellum is 

 about the length of the body. Generally two nucleus-like vesicles occupied 

 the interior, besides a clearer space around the position of the eye-point. 



Dr. R. W. Hargadine exhibited some beautiful crystals of hremato- 

 crystallin, prepared by himself after the method of Bojanowski, who 

 takes a quautity of blood drawn from a vein, or better from the 

 blood vessel of an animal after death, and places it from two to four 

 days in a cool place, until the blood corpuscles begin to form a 

 thick, dark red, or black mass. A drop of this fluid is placed on a 

 slide, covered, and placed in a dark place for several hours, when 

 the crystals begin to form. 



Dr. Chas. H. Thomas was elected a member of the Department. 



Oct Idth, 1868. 

 Director, Wm. Pepper, M. D., in the Chair. 



Twenty-two members present. 



Dr. H. C. Wood, Jr., called the attention of the Department to the manner 

 in which one of the plant inhabitants of the ditches below the city produces its 

 zoospores. The plant in question is filamentous, and grows in great numbers 

 attached to twigs, bits of dead grass, splinters of wood, &c., in stagnant or 

 partial stagnant water. 



At its maximum size it is very apparent to the unaided eye, and is of a 

 dark green or even blackish color. Such large filaments are perfectly opaque 

 and are composed of numerous cells. The base of the filament is narrowed, 

 and at irregular intervals in its length there are very marked contractions. 

 The younger filaments are uniform and composed of a single series of cells. 

 The zoospore is of the ordinary conical form, with the usual transparent space at 

 the smaller end, from which arise three long cilia. The living zoospore soon be- 

 comes attached by its pointed end to some support, its cilia withering away, 

 and commences to elongate at the expense of its transverse diameter. Atj^the 

 same time it acquires a cellulose coat. After a while the cell thus formed divides 

 transversely into two. Growth continuing, each of these cells after attaining'* 

 certain size, again divides transversely, and so the process goes on, until finally a 

 long filament is produced, which is composed of a single series of cells placed 

 end to end. When this filament has reached a certain stage of development, one 

 of two things occurs, either the cells begin to divide in the direction of their 

 length, or the production oi Zoospores takes place. In the first instance each cell 



