August 26, 1898.1 



SCIENCE. 



267 



are well wooded. The cliffs are vertical and 

 fringed at their base by the usual talus, which, 

 however, is made up of blocks of unusual size. 

 The cavern is formed by several huge rocks 

 overhanging the water so as to form a compara- 

 tively dark hole, and the space between the 

 under side of the sloping rocks and the water 

 varies from about two feet to not more than two 

 inches. The cavern faces the southwest ; it is 

 very irregular in shape, and at one point the 

 roof and walls reverberate in response to a deep 

 bass note. The water just at the entrance to 

 the cavern is 33 feet deep, and two or three 

 feet away 40 feet ; it is very transparent at con- 

 siderable depths. As the rocks overhang so 

 close to the water the optical effects can only be 

 seen by a swimmer, and it was while swimming 

 along the shore that I discovered the American 

 Blue Grotto three years ago. As one approaches 

 the mouth of the cavern the bluish color of the 

 water is noticeable, but the beautiful effects are 

 best seen by entering the opening and looking 

 outwards towards the light. The water varies 

 in color from Nile green through turquoise blue 

 and sky blue to deep indigo blue, and in all 

 these shades exhibits the silvery appearance, 

 when agitated, characteristic of the grotto at 

 Capri. A body immersed in the water has a 

 beautiful silvery sheen, similar to the reflection 

 of moonlight. The water has these colors at 

 all hours, but they are strongest when the sun 

 is in the zenith ; late in the afternoon the slant- 

 ing rays of the sun enter the opening and light 

 up the cavern, greatly diminishing the optical 

 effects. 



The water retains the characteristic color 

 (but without the silvery sheen) on cloudy days, 

 and even during rain, being especially strong 

 when fleecy white clouds bar direct sunlight. 

 The relation between the different hues, green 

 and blue, to the aspects of the sky, whether 

 clear or overcast, is not evident. 



Another pleasing phenomenon must be men- 

 tioned. Just below the water line, where the 

 rocky sides are lapped by the waves, the white 

 quartzite exhibits a brilliant siskin-green hue ; 

 this bright color is limited to a space about 

 three or four inches below the level of the lake 

 and to certain walls of the cavern. The bare 

 arm immersed in the water partakes of the 



green color when the light is reflected at one 

 angle, and of the silvery blue color at another 

 angle. The interior size of the cavern is not 

 easily given, but the face of the overhanging 

 rocks measures about 40 feet and they project 

 about 15 to 20 feet, and it is surprising that so 

 small a cavern can produce such a variety of 

 fine effects. 



The writer would like to learn, through the 

 columns of Science, whether similar blue grottos 

 are common at other American lakes. 



H. Careington Bolton. 



Lake Minnewaska, August, 1898. 



'the delusion of atavism.' 

 Dr. Brinton's recent remarks on the ' De- 

 lusion of Atavism ' recall Dr. Thomas Dwight's 

 paper on the ' Range and Significance of Varia- 

 tion in the Human Skeleton,' a paper which 

 may be read with much profit by those who 

 are bound to find some reversional character in 

 every anatomical abnormality. As Dr. Dwight 

 says, "if all animal resemblances are rever- 

 sions, the primitive ancestor must have been a 

 very curiosity shop of peculiarities. " 



F. A. L. 



SCIENTIFIC LITEEATUEE. 

 Technical Mycology. By Dr. Franz Lafae. 



With an introduction by Dr. E. Chr. Hansen. 



Translated by Chas. T. C. Salter. Vol. I., 



Schizomycetic Fermentation. London, Chas. 



Grifiin & Co., Ltd. ; Philadelphia, J. B. Lip- 



pincott Co. 1898. Pp. 405, with 1 plate and 



90 figures. 



The appearance last year of the first volume 

 of Dr. Lafar's Technische Mykologie relating to 

 fermentations induced by Schizomycetes marks 

 the gradual development of bacteriological sci- 

 ence along other than medical lines. The in- 

 terest that is attached to the study of these 

 micro-organisms in other than their patholog- 

 ical relations is rapidly increasing, and we may 

 hope that such works as these will stimulate 

 investigation and study in a very promising 

 field of research. The translation of this work 

 into English by Salter will unquestionably be 

 welcomed. 



The scope of the work is the utilization of 

 micro-organisms in the arts and manufactures. 



