1889.] BOTANICAL GAZETTE. 29 1 



stamens and style about as long as the upper lip of the corolla, which is 

 uniformly of a pale lilac. A second form has narrower, more deeply 

 sinuate leaves ; flower clusters larger ; corolla on the three lobes of the 

 low r er lip irregularly spotted with purple; style well exserted, its two 

 lobes rather longer than in the first form. A third form has leaves and 

 flower clusters as in the second form, but the flowers have no spots on 

 corolla, and style not exserted, but only as long as upper lobe of corolla. — 

 John M. Holzinger, Winona, Minn. 



A deep-water Nostoc. — With the first gales of November and March 

 each year there appears upon the shore of Lake Michigan an abundance 

 of an interesting form of Nostoc. It was first observed in 1864 by Pro- 



fessor Oliver Marcy. Thrown out upon the shore by the waves, it ap- 



pears as small brown, purple and green balls or thalli. These are not 

 always round, but frequently ovoid, and the larger specimens broadly 

 flattened. Generally they are globose, with a firm, tough exterior or per- 

 iderm. Color varies from light blue-green and flesh-color to brown or 

 purple, the browns prevailing. They are from 2 to 20mm. in diameter 

 the usual size being 5mm. broad. Examined microscopically, the trich- 

 omes are thin and regular ; diameter of the heterocysts, 5 to 8.75/^ ; aver- 

 age, 6.87//; diameter of cells, 2.5 to 5.6/*; average, 3.56^. 



In 1871 specimens were sent to Harvard College, with inquiries as 

 to its species. Dr. Gray replied, "The plant is Nostoc sphteroides of Kutz- 

 ing. Pray keep a look-out for it from year to year. It ought not to grow 

 in deep water." This determination proved erroneous, for in Kiitzing's 

 description the trichomes are said to be swollen between the heterocysts, 

 which is not true of our Nostoc. In 1882 Professor S. A. Forbes, exam- 

 ining dredgings from the lake, found a Nostoc answering the general 

 description of our lakeshore plant, and reported the same in Science for 

 June 1, 1883, as Nostoc pruniforme. In reply to our inquiries, he said, " It 

 was abundant all along the city front as far out as ten fathoms deep." He 

 referred it to Dr. Wolle, who replied, " I judge rather by your description 

 than by the samples sent that they are Nostoc pruniforme: 9 When Dr. 

 WolleV " Fresh Water Alga* " appeared, this Nostoc was not mentioned. 

 Thinking it worthy of further attention, specimens were sent to him, to 

 Dr. Farlow, and several others. In the correspondence which followed, 

 the plant received various names. Dr. Wolle thought it might be N aer- 

 xdeum, while to others it seemed to have the characteristics of N. ZeUer- 

 stedtii and N. verrucosum. Dr. Farlow, having examined both the autumnal 

 and spring stages, writes, July, 1889, " I could not make the measure- 

 ments of the plant of last year agree with those of N. pruniforme, nor can 

 I now, on re-examination. Dr. Barnet, however, is inclined to believe 

 that it is really an autumnal stage of N. pruniforme, although it does not 



agree with descriptions of the type." 



It should be stated further, that the base of every thallus shows a thin 



incrustation of calcium carbonate. 



