Studies in General Physiology Volume 2 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 Excerpt: ...that after the treatment with Mg ions the character of the segmentation was much more normal than after the treatment with K and Na or Ca ions. The K ions were nearest the Mg ions in their effect. The Ca ions were the most unfavorable. The former experiments of Norman had also yielded the result that the Mg ions were the most harmless for the segmentation of the sea-urchin egg. IV. THE ARTIFICIAL PRODUCTION OF NORMAL LARVjE (PLUTEl) FROM THE UNFERTILIZED EGG OF THE SEA-URCHIN The most serious danger in experiments with unfertilized eggs is the possibility that the sea-water or the instruments contain spermatozoa. It is imperative to guard against both possibilities. The sea-urchins have practically died out in the immediate neighborhood of the Woods Hole laboratory, and we have to send out the steam launch to collect them. For this reason even at the height of the spawning reason there is little danger of the sea-water containing spermatozoa in such quantities as to interfere with experiments on unfertilized eggs. Moreover the danger that the spermatozoa contained in the sea-water of the laboratory may interfere with experiments on unfertilized eggs is not very great, even at the height of the breeding season. This is shown indirectly by the fact that in the experiments described in the previous chapter not a single egg was fertilized through contamination of the sea-water with spermatozoa. The spermatozoa if scattered in sea-water soon lose the power of impregnating the egg. Gemmill found experimentally that this occurs in less than five hours after the spermatozoa leave the testicle.1 My experiments were carried on after the breeding season was practically over, in September, when the majority of sea-urchins contained practically no more eggs. I had alrea...