Febeuaey 7, 1896.] 



SCIENCE. 



203 



fact of pathology, 'which by itself would be 

 enough to settle the question — the rare cases, 

 namely, of metamorphopsia. It sometimes 

 happens that a piece of the retina is detached 

 by means of a wound, and that it afterwards 

 grows on again in a wrong position, and vision 

 is regained, but things are out of place. A case 

 has just been reported before the Italian 

 Ophthalmological Society, in which distorted 

 vision occurred over the portion of the retina 

 affected, the inversion being from right to left, 

 but not also up and down (showing, therefore, 

 in addition, that the retina can still perform its 

 function when it is wrong side out). Such 

 cases as this are also plainly incompatible with 

 a projection theory. C. L. F. 



Baltimore, Md. 



marsh gas under ice. 



Prop. Remsen's note under the above title in 

 Science for January 24th, p. 133, is of more than 

 local interest. So far as I am aware, the phe- 

 nomenon of gas spurts through ice has not be- 

 fore been described. As early as the winter of 

 1878-'79 the writer observed, at West Summit, 

 N. J. , the ice on a bog covered with miniature 

 craters and mounds of new ice. These ice ac- 

 cumulations took place about vents up through 

 which came water and gas bubbles, the former 

 charged with the brick-red ferruginous deposit 

 at the bottom of the bog. Frequently the vent 

 was along the side of a blade of bog grass. 

 During the winter, the surface of the ice on the 

 bog become very rough by the additions made 

 in this way. The flocculated bog ore thus 

 brought to the surface was, during times of rain 

 and thaw, washed into the neighboring stream, 

 so that the process tends to retard the growth 

 of bog ore deposit. Similar outbursts may be 

 observed during the winter where a coating of 

 ice forms over a lawn which has been treated 

 with ordinary manure in the autumn. Gas 

 spurts break out after a period of continued 

 cold, and the surface of the ice becomes dis- 

 colored with the products urged up by the 

 escaping gas. An instance of this action was 

 to be seen on the grounds of the Museum of 

 Comparative Zoology at Cambridge last winter. 

 It would be of some importance in glaciology 

 to ascertain what part this escape of gas plays 



in the breaking-up of the ice on shallow ponds 

 and lakes. J. B. Woodwoeth. 



Cambridge, Mass., January 27, 1896. 



■■ ETHNO-BOTANIC GARDENS. 



The purposes of a museum are twofold : First, 

 it is to be a place of instruction where the gen- 

 eral public can resort for information as to ob- 

 jects from distant or foreign lands; second, it 

 is to be a place for scientific research. A mu- 

 seum fulfills its purpose best when both of these 

 objects are kept in view. The collections should 

 be so arranged as to teach the public by object 

 lessons, and at the same time be adapted for 

 scientific work. Most of our colleges have kept 

 these objects prominent in the fore front, and 

 many of them have arranged synoptical collec- 

 tions for the instruction and edification of visit- 

 ors. Several of the larger institutions of learn- 

 ing, notably Harvard and the University of Penn- 

 sylvania, have buildings set aside for museum 

 purposes, and it is, therefore, to them that we 

 must turn when we desire to study the operation 

 of museums with educational views and aims. 



The University of Pennsylvania proposes to 

 erect, in the near future, a series of museum 

 buildings, which will bring the institution into 

 closer touch with the general public, and at the 

 same time give the students in the several de- 

 partments a chance for original research work. 

 It is intended by the University authorities to 

 place the buildings in a public park to afford 

 better light for exhibition purposes, and so as 

 to display to better advantage the architecture 

 of the structures. A separate building it is 

 planned will be devoted to archseology and eth- 

 nology. Such a building is badly needed at 

 present, for the anthropological collections in 

 general have accumulated to such an extent as 

 to crowd the space in the library now allotted 

 to them. 



The opportunity is presented when these 

 buildings are erected to construct an ethno- 

 botanic garden in connection with the public 

 park. It is to the outlining of the purposes of 

 such ethno-botanic gardens, in general, that 

 this article is directed. 



1. Only aboriginal American plants should 

 find a place in such a garden. No plant can be 

 found more graceful than maize, a grass asso- 



