The viscosity of the hyaline (granule-free) cytoplasm of the immature egg of Spisula (Lamellibranchia) was determined by use of the Einstein equation for Brownian movement. The value obtained was 4.3 centipoises. Thus this protoplasm has a viscosity similar to that of a concentrated protein solution. The viscosity of the entire cytoplasm, granules and all, is much higher. This is due to the great concentration of granular material. Study of the movement of the large germinal vesicle through the cytoplasm under the influence of different centrifugal forces indicates that the viscosity of the entire cytoplasm, granules and all, does not decrease as the shearing force increases. Hence, apparently, the entire cytoplasm behaves like a true Newtonian fluid--at any rate there is no evidence of thixotropy. The idea that protoplasm is typically a gel is not in accord with the evidence presented here. Additional evidence for the fluidity of protoplasm is provided by earlier information about the osmotic behaviour of cells, the formation of ice crystals in protoplasm, the rapid dispersion of aqueous solutions injected into cells, the outflow of protoplasm from cells broken in calcium-free media, and by magnetic studies.
Call for papers: Cell and Tissue Polarity
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We are welcoming submissions for our next special issue, which will focus on ‘Cell and tissue polarity’ and will be guest edited by David Bryant. Submission deadline: 15 July.
The Forest of Biologists
We are excited to announce the launch of The Forest of Biologists, a new biodiversity initiative created with support from the Woodland Trust, aiming to counteract nature loss and safeguard some of the most critically endangered ecosystems for future generations. For every Research Article and Review/Commentary article that is published in JEB (and our sister journals Development, Journal of Cell Science, Disease Models & Mechanisms and Biology Open), a native tree is planted in a forest in the UK.
Propose a new Workshop for 2025
Do you have an idea for a Workshop? We are now accepting proposals for our 2025 Biologists Workshops programme. As the scientific organiser, your involvement will be focused on the science. We'll take care of all the logistics. In 2025 we'll continue our efforts to diversify our Workshop programme and will be reserving one of our Workshops for an application from a Global South (GS) country to host an event overseas.
Editorial: Publishing where it matters
Cell Scientists to Watch
As a community-focused journal, Journal of Cell Science is keen to support the next generation of cell biologists. Check out Cell Scientists to Watch, our interview series featuring talented researchers who have recently set up their own labs.
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