116 



SCIENCE. 



[N. S. Vol. XXIII. No. 577. 



developed normally, will, if impregnated by 

 two spermatozoa, develop pathologically. 



2. As I have previously stated,' the isolated 

 blastomeres of dispermic eggs differ extremely 

 in their developmental potency; but it was 

 formerly not possible for me to follow the 

 single blastomeres in their development so as 

 to be able to assert with complete positiveness 

 that there had not been during the isolation 

 an unequal degree of injury to the blastomeres 

 which might have been the cause of the in- 

 equality of the development. This I have 

 succeeded in accomplishing in my new experi- 

 ments. It has been possible to show that the 

 early development up to the blastula stage 

 proceeds identically in the isolated blastomeres 

 of a dispermic germ, and that only later does 

 one partial germ strike out in one direction, 

 the other in another direction. 



3. In connection with this I have studied 

 thoroughly the early development of uninjured 

 dispermic germs and they confirmed the cor- 

 responding original similarity and later un- 

 likeness of the single germ areas. 



4. A further question concerning the devel- 

 opment of dispermic germs was whether the 

 so-called primary mesenchyme cells which later 

 group themselves to form the regular mesen- 

 chyme crown for the formation of the cal- 

 careous skeleton always occur only in that- 

 area of the germ in which they arise, or 

 whether the mesenchyme represents an indif- 

 ferent material, the cells of which are distrib- 

 uted by accident to the crown of mesenchyme. 

 By means of the difference in size of the cells 

 and nuclei in dispermic germs, it became pos- 

 sible for me to decide this important question 

 in favor of the last alternative. 



5. Against the theory which I formerly ad- 

 vanced upon the basis of my experiments on 

 dispermic development of the different valence 

 of chromosomes, the objection might be raised 

 that it was not, as I had suggested, the false 

 combination, but the incorrect number of the 

 chromosomes which was of pathological sig- 

 nificance, for it might be said that only when 

 the requisite quantity of chromatin is present 



' ' IJber mehr polige Mitosen als Mittel zur 

 Analyse des Zellkerns,' Verh. d. phys.-med. Ges. 

 Wiirzlttrg, 1902. 



that the proper relation of nucleus and proto- 

 plasm can exist which is necessary to the nor- 

 mal functioning of the cell. In order to 

 exclude entirely this objection it must be 

 shown that for any given quantity relation 

 of nucleus and protoplasm in the starting cell, 

 the proper relation of the two constituents 

 can be reached in the larva cell. This could 

 be proven by the rearing of fragments of eggs 

 of all sizes in which, therefore, the amount of 

 the nuclear material remaining constant vari- 

 ous amounts of protoplasm were present. 

 These experiments were so carried out that 

 the egg fragments were reared in quantities 

 and in these cultures every thinkable size of 

 normal larvae was found. Again, various 

 sized egg fragments were measured accurately 

 and reared isolated, and these also developed 

 into normal laryse of all sizes. 



6. The important task which I had set my- 

 self was the following of dispermic eggs in 

 which only one sperm nucleus united with the 

 egg nucleus while the other remained inde- 

 pendent. I succeeded in rearing twenty-two 

 specimens in which this rare and theoretically 

 especially important type of dispermy oc- 

 curred. From these I obtained a considerable 

 number of gastrulse and plutei. These larvae 

 consist of one part with large nuclei and one 

 with small nuclei, and by this mark it may be 

 determined with complete certainty what part 

 contains ' paternal nuclear substance and what 

 part contains, paternal and maternal nuclear 

 substance combined. 



The various experiments enumerated will 

 enable me to finish my work on double im- 

 pregnation, and I hope that the completed 

 memoir will be published in the spring of 

 1906. 



Charles S. Minot, 



THE OONORESS OF THE UNITED STATES. 

 On January 6 a bill was introduced by 

 Mr. Kahn, to provide for celebrating the four 

 hundredth anniversary of the discovery of the 

 Pacific Ocean by Vasco Nunez Balboa by 

 holding an international exhibition of arts, 

 industries, manufactures, and products of the 

 soil, mines, forest and sea, at the city of San 



