156 



THE AMEEICAN MONTHLY 



[August, 



was observed reaching up to the sur- 

 face of the water. It was two or 

 three feet in length, and bore a pe- 

 cuHar flower at the end. This was 

 the female flower of Vallisnei-ta, a 

 very interesting object for study ; it 

 was quite a surprise to us, as the plant 

 does not usually flower so early as 

 July. Looking toward the shore, the 

 water was covered with an innumera- 

 ble quantity of wjiite specs, which at- 

 tracted our curiosity. Rowing up to 

 them, we found that they were the 

 male flowers of Anacharis. These are 

 very curious flowers. The long, tu- 

 bular perianth, sometimes two or three 

 inches in length, reaches from the 

 axil of a leaf to the suface of the 

 water, and bears the stamens above. 

 It would easily be mistaken for the 

 flower-stem, but it is really the tubu- 

 lar perianth. These flowers were very 

 abundant, so that the water appeared 

 white with them. The pollen-grains 

 were numerous, and could be seen 

 floating about on the water in little 

 clusters resembling snow-flakes. Po- 

 tamogeton was abundant, in sev- 

 eral forms, and the common arrow- 

 plant, so named from the shape of the 

 leaf, Pontedaria cordata, which is also 

 good for large aquaria. This plant 

 should be set in a flower-pot, with 

 suitable soil in which to root, and then 

 submerged, either wholly or in part. 



Among the algs, two species of 

 Oscillariaceae were found quite active- 

 ly moving Oscillaria tenuis and littor- 

 alis, and Lyngbya majuscula. The 

 most interesting specimen of all, 

 however, was a species of Ulothrix^ 

 a very common, filamentous, green 

 algae, in which the cells are about as 

 long as they are wide. It was inter- 

 esting because when we examined it, 

 at about seven o'clock the next morn- 

 ing, the process of giving off swarm- 

 spores had just begun. The entire con- 

 tents of each cell in whole filaments, 

 quickly formed into green, spherical 

 masses, which began to move 

 about in the confined space within the 

 cells ; soon the cell-walls ruptured, 

 and the contents escaped as very ac- 



tive swarm-spores, somewhat elong- 

 ated in form, and furnished with four 

 long, whip-like appendages, or flagel- 

 la, by means of which they could 

 swim about. They measured 5. A'S to 

 8/" (.00022 to .00033-inch in diame- 

 ter). After a while they become 

 attached to some object, lose their 

 flagella, elongate and subdivide, form- 

 ing new growths of Ulothrix. 



Croton Water in August. — The 

 Croton water which is now supplied to 

 this city possesses no offensive taste 

 or odor, although there is a consider- 

 able amount of suspended matter to 

 be collected by filtering it. This is 

 another fact tending to prove that the 

 peculiar odor sometimes observed 

 is caused by certain plants which 

 are not always present, and not by 

 the decomposition of vegetable mat- 

 ter of all kinds. We have lately 

 studied the algae found in a few fil- 

 terings, although the list is not com- 

 plete, it may still be of interest to 

 observers in other cities. In naming 

 the algae we have been assisted by the 

 Rev. Francis Wolle, who has observed 

 most of the forms here mentioned. 

 Phycochromophvce^. 



Dictyosph(zrium Eherenbergii. 



Coelosphcerium dubium. 



Merismopedia {glauca ?) 



Oscillaria tenuis. 



Froelichii. 



SphcErozyga polysperma (.?) 

 Chlorphllophyce^. 



Palmodactylon variuf?i. 



Paphidium poly7norphum Y.falcatum 



Chlorococcuni gigas. 



Polyedrimn trigonum. 



Scenedesmus quadricauda. 



obtusus. 



Pediastf'um simplex. 



biradiatum. 



pertusum. 



Goniuni pectorale. 

 Cosmarium subcrenatu?n. 



tetrophthalnium. 



Staurastrum Iceve. 

 Sebaldii. 



gracile. 



Micrastej'ias truncata. 



