September. 1911. 



KNOWLEDGE. 



367 



exactly such lines. On inquiry I ascertained from 

 the observers at South Kensington that man\- of 

 these lines certainly did come from iron, and there 

 were also some that came from titanium. 



The observers at South Kensington noticed a 

 remarkable fact with regard to the broad hydrogen 

 lines. Thev seemed streak\- : towards the edges 

 there seemed to be especial bands of greater 

 intensity. In the theory of the third body, I have 

 shown there is a line along \shich, in both directions, 

 gas will be extruded. Axial Extrusion is the name 

 we have given to this phenomenon. In the stud\- of 

 the origin of the universe, it is assumed to account 

 for the origin of the white polar nebula that is dis- 

 tributed at each of the poles of the Milk\' \\'a\". 

 This principle also permits the hydrogen gas that is 

 compressed at the centre of the third body to be 

 expelled in the two directions polar to the 

 plane of rotation. Doubtless it is these two vast 

 streams of ejected hydrogen that give these two 

 ribbons of intensity on the broad hydrogen 

 bands. The obser\ers at South Kensington 

 also noticed minor ribbons of luminosity, and a 

 careful study of the form of the third body 

 shows other weak places, where, in a less effective 



way, hydrogen may be sent out as vast streamers. 

 There are quite a sheaf of other points of interest 

 and coincidences, and some show themselves in 

 connection with the pre-existing more or less 

 annular spiral nebula that was lit up by the flash of 

 Nova Persei, and that showed itself progressively in 

 extending circumferences. Light, with its speed of 

 one hundred and eighty-six thousand miles a second, 

 for months progressively lit up the coils of that 

 stupendous nebula, which I believe had been left 

 behind in a previous impact of the same two 

 gigantic suns, that by recurrent impact had pro- 

 duced the flash of Nova Persei. Deduction suggested 

 also that extruded gas from the third body should 

 generally pass through the stage of being a planetary 

 nebula. And here, again, we have the same 

 coincidences, but our account is already too long 

 and we must conclude by stating that from its 

 extreme brilliancy and its evanescence. Nova Persei 

 was almost certainly formed by a very small ratio 

 graze of two extremeh" massive suns, whilst Nova 

 Aurigae was a moderately-deep graze of suns of much 

 smaller mass. In the next number the coincidences 

 of astronomical phenomena, with the deductions 

 relating to the two torn suns, w ill be debated. 



CYTOLOGY AND EMHRYOLOGY 1\ THE EN'CYCLOPAEDl.A 



BRITAXNICA. 



The scientific articles in the last edition of "The Encyclo- 

 paedia Britannica " cannot fail to be of the greatest interest to 

 the readers of this journal. They are clear and concise, and 

 thoroughly up-to-date. That on Cytology, is of the highest 

 importance, for " it is to the cell that the study of every bodily 

 function sooner or later drives us." Space will only permit us 

 to refer to one of the many interesting points elucidated in 

 this article. \'arious views have been expressed as to which 

 of the complicated processes which take place during nuclear 

 division is fundamental and initiative. " The experiments 

 of T. H. Morgan and E. B. Wilson, in which numerous 

 centrosomes and asters are caused to appear in unfertilised 

 sea-urchin eggs by a brief immersion in a 13 per cent, solution 

 of magnesium chloride in sea-water, as also the possibility in 

 many cases that even in normal fertilisation the cleavage 

 centrosomes may arise de novo, make it no longer possible to 

 regard the centrosome as a permanent cell-structure." " In 

 the spermatogenic cells of Ascaris, A. Brauer has shown that 

 the chromatin granules divide while still scattered over the 

 nuclear reticulum and before either the formation of a spireme 

 thread or the division of the centrosome." Clearly then, the 

 formation of the achromatic spindle has for its purpose, not the 

 division of the chromatin, for this has already occurred, but 

 its distribution to the two daughter nuclei. 



The article on Embryology is likewise full of interest. The 

 question of the determination of sex has been much debated, 

 but the balance of evidence, we are told, appears to favour 



the view that sex is an unalterable inborn character and does 

 not depend on nutrition or other external condition. " Thus 

 those twins which are believed to come from a splitygote 

 are always of the same sex, members of the same litter which 

 have been submitted to exactly similar conditions are 

 of different sexes, and all attempts to determine the sex 

 of the offspring in the higher animals by treatment have 

 failed." 



Various structures and organs appear during development 

 to disappear again without representation in the adult form, 

 but the writer of the article on Embryology gives Uttle (luarter 

 to the recapitulation theory which attempts to explain this by 

 asserting that the embryonic history of the individual is but a 

 shortened Recapitulation of the ancestral history or history of 

 the race. " A disappearing adult organ is not retained in a 

 relatively greater development by an organism in the earlier 

 stages of its individual growth unless it is of functional 

 importance to the young form." Gills, for instance, are 

 retained in the tadpole while they are lost in the frog, 

 because they are of use to the tadpole, that is, to the larval 

 form. Where organs are retained in a better developed state 

 in the embryo than in the adult, it is simply because they have 

 been of use to the ancestors in their larval form, though of 

 no use to them in the adult, and have become in this way 

 impressed upon their development ; and only if they ha\ e been 

 of value to the larval form in former generations is there any 

 possibility of their retention. 



