224 



POPULAR SCIENCE MONTHLY. 



the egg, is incited by chemical stimulus; 

 and several observers before Loeb had 

 shown that when unfertilized sea- 

 urchin eggs are treated by the addition 

 to the sea-water of various substances, 

 such as strychnine or chlorides of 

 sodium or magnesium, they may under- 

 go some of the preliminary changes of 

 development and may even segment. 

 Loeb was able to induce complete and 

 normal development by first bringing 

 the eggs for about two hours into a mix- 

 ture of sea-water and a weak solution 

 of magnesium chloride, and then trans- 

 ferring them to normal sea-water. Eggs 

 thus treated segmented and underwent 

 a development which, though somewhat 

 slower than usual, was otherwise nor- 

 mal and produced perfect larvae. This 

 effect can not properly be called fertili- 

 zation in the ordinary sense of the word, 

 but is rather to be regarded as artifi- 

 cially induced parthenogenesis. It points 

 unmistakably, however, to the possibil- 

 ity, or rather probability, that in nor- 

 mal fertilization the spermatozoon in- 

 cites the egg to development by bring- 

 ing to it certain definite chemical sub- 

 stances; and Loeb gives reasons for the 

 view that these substances are probably 

 in the form of ions, concluding that 

 these and not the nucleins are essential 

 to the process of fertilization. A highly 

 suggestive new field for work is opened 

 by these experiments. 



Astronomers can not bring the phe- 

 nomena they study into the laboratory 

 or test the behavior of the heavenly 

 bodies under artificial conditions. They 

 have to be satisfied with such oppor- 

 tunities as nature gives, even though 

 she bestows them as meagerly as she 

 does solar eclipses. Consequently, the 

 total eclipse of the forenoon of May 28th 

 has been the object of much preparation. 



Most of the important astronomical ob- 

 servatories in this country will have 

 parties stationed along the path of the 

 eclipse from New Orleans to Norfolk, 

 Va. Many European parties will ob- 

 serve the eclipse in Portugal, Spain and 

 North Africa. It has been pointed out 

 by Prof. R. W. Wood and Mr. A. L. 

 Rotch* that there are several important 

 physical observations to be made apart 

 from the astronomical observations on 

 the sun's corona described by Professor 

 Bigelow, in the May number of this 

 magazine. Just before and after totality 

 alternate bright and dark bands are ob- 

 served sweeping across the country. It 

 is hoped that by the cooperation of a 

 number of observers more complete and 

 exact data concerning this phenomena 

 may be gathered and its explanation 

 found. The changes in the wind noted 

 during eclipses will also be observed to 

 ascertain whether the sudden cooling of 

 the atmosphere by the passage of the 

 moon's shadow is a sufficient explana- 

 tion of the so-called 'eclipse wind.' 

 Those who know nothing about theories 

 of the corona or of the 'eclipse wind' 

 will be interested in the more obvious 

 phenomena and in some cases, in the op- 

 portunity to take such a photograph as 

 can not be duplicated in this country 

 until 1918. The most favored ones are 

 those who live in the fifty-mile belt of 

 the total eclipse, but the sun will be 

 seen nine tenths covered in the eastern 

 and southern States, and will be six 

 tenths covered to those in the least fa- 

 vorable locality of the United States, 

 the extreme northwest. The proper 

 methods of observing and photographing 

 the corona were described in Professor 

 Bigelow's article on the eclipse in the 

 May number of the Popular Science 

 Monthly. 



* In ' Science,' Apr. 27th and May 11th. 



